Anyone run a auto?

The 47 and 48 RH/E transmissions are tanks, there is no manual detent position for overdrive. If you end up going to JW ultrabell route to adapt it to your engine, the ultrabell will only fit a 10" converter - which isn't mentioned anywhere. Not many people make a lockup converter that is 10". Getting someone to build a lockup converter that will take real power will probably require a midplate/spacer, so factor that in when you cut the tunnel/crossmember to fit it in there. This trans can be made as strong as you need it to be but if I had to do it over again I'd go with a GM conversion trans. Much more aftermarket support.

Why is a manual not the best idea?
How about a G-Force GF-5R 5-Speed or Jerico 5 speed?
Dog Rings and Sliders can be fun.

This build will be interesting, please keep us (me) updated on how it goes

During a med-speed typical pylon lot autocross, you want to avoid shifting so you won't disrupt the driving and transition of the car. On a hi-speed road course you have more time in the straights (although some may still be curved straights) to aford the shifting. A manual trans will allow more power to be used, whereas the automatic does take some away. Regardless which type of course you're on (med-speed r hi-speed), and which type of trans you have, you want to avoid disrupting the flow and steadiness of the car if/when ever shifted... try to concentrate on being smooth. My 727 has been bullet proof and it shifts fully automatic or manual up/down... I can trail brake more easily with an automatic, but manuals take more skill to master their advantages. Winners can be either trans (auto or manual)... the nut behind the wheel makes the final decision on how well the car finishes.

So is a well set-up auto smooth enough? Seems like a quick change rear end is the real answer for different tracks.
And to the OP, I'd put a deposit on the passon 5 spd and call it a day, run anything in the meantime to sort out car and driver first.

Maybe try one of these paddle shift ones...

http://www.twistmachine.com/index.php?main_page=product_info&cPath=6&products_id=12

With autocrossing, in particular med-speed pylon events, rarely are you ever on full-throttle (and even if you are it isn't for any length of time beyond a few short seconds) because you have constantly manuevering the car with transitions through the course. If you have to shift, say from 1st into 2nd, or into 3rd, pending your RPMS (trans gears and rear axle ratios, and tire diameters which all reflect the rpm range), then shift repeatedly back down, up, down, etc... all your doing is waisting time and not allowing the best concentration on the course to manuever through.

With a road course, for lapping sessions, you have can more easily allow the shifting as the courses aren't as demanding to negotiate and concentrate where/when/how to position the car.. all that is still critical on a road course (at higher speeds), but you have more time to allow for shifting. Also, a road course can take better advantage of a manual transmission taking less horsepower away from the engine than an automatic.... but the difference isn't dramatic unless you're concerned with getting that last infinite time difference upon your competitors. Heck, even with an automatic, a better driver can out-perform another driver who has a manual... its the nut behind the wheeeelllll!

Again, regardless automatic vs. manual, the driver (the "nut behind the wheel") makes the biggest difference in the performance of the car. An automatic can win one day and a manual can win the next day... etc, even if the drivers are the same and the cars are the same.

Quick change rear ends? If someone has the time, and commitment, and equipment, etc.. your choice. Our common 8.75 rear ends are my type of quick change rears. And, as spoken of before, clubs have different "rules" of what's allowable, etc.

Best advice.. simply adapt your driving style to the car and trans, and the courses you'd run on ... pylon courses will almost always change per every wknd event, but road courses are typicaly the same every time you visit. Consider avoiding constantly having to shift... less is better!

Does an auto require any extra over and above cooling in auto or road race use? How about converters and stall speeds for same use?

In pylon autox (med-speed), you can get away without any additional cooling (auxiliary trans cooler) since you're only on the course for ~30-45, maybe 60 seconds ata time, so it doesn't realy get too hot. in fact, adding an auxiliary trans cooler would be adding weight to the front of the car and that's exactly where you don't want to be adding weight (contributes to understeer). For many years in serious competition autox, I only ran a small aux-trans cooler, and eventually removed it only for the weight reduction.... remember.. every little bit of weight reduction all adds up to more weight loss.. = faster (lower) timed runs.. looking for that every little bit of competitiv edge possible.. especially on a national levl of competition.

In road course lapping sessions, or even solo-hi-speed road course events, its a good idea to have an auxiliary trans cooler since you're out there for longer periods of time pushing hard... you do want to protect the trans fluid from excessive hi-heat. If you'd really want to, you could eliminate that extra cooler for weight savings, but... you have to make a judgement what it's worth.. maybe the trans fluid simply would have to be changed/flushed more often without an extra cooler, pending how hard you drive/race. Having a trans fluid temp gauge is good idea (although it ads a fraction of weight!). Since I've been driving my Chally on various road course lapping events, as well as back on the street/hwy a little (off the trailer in other words), I've recently installed a new trans cooler.. one from a Cummins Dsl P/U.. even has the Chrysler logo and part number on it.. and it fits perfectly (price was right, too... free from a close racing buddy having a spare new one!).

A word of caution on extra volume trans pans -- too much fluid can run up and out of the dip stick when you corner and/or decelerate/corner making left-turns/curves... I've replaced the old deep pan with a stock depth factory pan and that grossly eliminates the excess fluid running out the dip stick... I even installed a new tube/locking dip stick and that helps, but doesn't stop all of excess fluid from a deeper pan.... so.. I suggest only using a factory-depth/volume pan... not any of the deeper pans.. too much fluid! (remember, too, I'm talking hi-G-force, such as competition events).

Excessive heat deteriorates the fluid and thus contributes to trans failure. Well, smaller torque converters also create increased heat.. but, they don't offer low-end torque due to their increased slippage. You need to know what you cam is designed for and the rpm range you'll normally drive the car in.. so, if you're driving locally on the street/hwy, you don't want the torquconvrtr to be slipping due to the stall. forget the hi-stall converters for autx or road course events.. kekk close to stock, such as something that is hooked at ~2000, maybe 2500 or ~2800 max... anything jhigher and you're only asking for eventual trouble, not to mention less drivability/responsiveness (smoothness) when you need it at the lower rpms.

Now, if you'd really want the best advantage of weight reduction... favor a manual trans (aluminum case, of course!).. since you'd further not have any need for a front mounted aux-trans cooler.

Then again, when I bought my Chally (in 1975!), it was and remains an automatic... I dream ($$) of maybe someday converting to a 4-5spd stick, and that would be cool as the pistol-grip handle is awesome and i used to own/drive a 4spd Chally as a daily driver, but the cost, hassle, etc is not worth it to me... I still race and compete succesfully with the automatic. but I do have a pistol-grip shift handle... cool!!

So Mitch, is your (or others) driving style two foot/go kart style with auto? It seems like a big plus in autocross. No one needs to sell me on road race auto, after first seeing Jim Hall make it work at Sebring in 65.

2 footing is always best. Lots of times I would press on the throttle while braking, keeps the rpm up in the torque range.

Yes... 2-footing the med-speed autocross competition events can be fastest with my automatic... as well as keping the rpms up... its a technique that you learn and it becomes 2nd nature. On road courses, I'm more careful about 2-footing as I don't want to overheat the brakes, but I still use both feet.