IF the budget matters, the 518 goes in for 1/2 the price of the GM based ODs. And you do not have to mod the tunnel. With the torque that our big blocks make, the difference in 1st ratios is a non issue.

What is there to think about?

The car below had a Gear Vendors attached to the 727. The OD wasn't all that great at .78. I JUST bought a Tremec 5 speed kit from Silver Sport....

Like I said, I'd rather keep it all Ma Mopar and the other thing to consider is that I'm hoping I don't have to mod the tunnel was the other thing. The tranny will be behind a 400 stroked to 470. Have you done this DaveRS?

Yes, I have. I posted a few details in an earlier post in this thread.

You’re absolutely right, even the 518 doesn’t make financial sense for most.
I struggled with making the swap, because I’m cheap and always feel compelled to do a cost benefit analysis.
The 1 thing you can’t put a price on is enjoyment. I found myself not driving the car as much because it was so annoying running along at 4k RPM in the slow lane getting passed by minivans while my teeth rattled.
My only regret is not doing it sooner.
If you’re only doing city driving and stoplight to stoplight runs, save your money.

BDW nailed it.

I will also add your money invested into an engine build will last much longer. Overdrive is directly responsible for today's engines lasting 200,000 miles.

The days of a833's, 727's and 4.10 dump truck gears are over.

I finally pulled the trigger on a 518 for my 71 Barracuda when one popped up at a local you-pull-it. $250 and a fun afternoon later we had it out and loaded. I was on the fence for quite awhile, looking at all the different 4LXXe bell housing swap options. I wanted electronic control, but the fairly direct shifter hookup to my slapstick is a great trade-off. I plan to use 4.56s, which will give plenty of starting line ratio while still manageable with the OD for the highway. 3.06 for the 4L60 was actually a concern for me, that's quite a steep hit and I'm not planning to run Stock Eliminator.

However, am I wrong in thinking the low gear 727 gear sets would work in the 518s?

Curious what the angle of the engine/trans is without modifying the tunnel. The 518 is even larger than most transmissions at the rear, and with it pointed down enough to clear the torsion bar crossmenber and floor, it must angle down at quite a large angle.

Don't forget about the lil 42RH. Smaller body for a better fit and has the 2.74 first gear. You will definitely need to beef up the internals, but if you are doing a rebuild anyway, won't be that much more.

My 518 went in my Challenger and matched the 727 angle without mods to tunnel.
I shimmed it to 2 degrees downward.

How can you shim it down? That is not possible. A shim would raise the tail end.

Wow, surprisingly good angle for no cutting of the tunnel metal.

FYI, I did the A518 swap on my 73 Cuda 3 years ago. I was able to get a transmission tailshaft angle of 3.2 degrees down (below horizontal) without cutting the torsion bar crossmember. Any angle less than that will require notching the crossmember. So check for interference carefully before you install your transmission.

This is the point i was trying to make
My car is not a long distance driver. More or a local cruise in and around town. Playtoy type of car.

I might take it to Phoenix once or twice a year.....maybe.
But.....if i do. Ill live with it at 65mph. .
Or ......I'll take back roads and see the country.
Anything farther than that. Ill rent a truck and trailer and haul it .

Unless you have 2.73s in your car, spend a weekend with an OD unit in your car and you will see what you have been missing. It makes it a different car. A better car and by every measure. Other than effort and money, there is absolutely no down side.

Yep....it was Randy. Hate that he ain't here anymore!

It may seem like crap on an rpm formula but that 2.45 is what we consider close ratio. This is ideal for powerful engines. You put the deep ratio in the rear and now you have less rpm drop between gears.
The 3 something ratios you speak of are from an era of gutless engines. The 4L60E and 833 OD are for moving heavy vehicles with weak engines off the light and with no consideration for big rpm drop between gears.

I hear what you are saying but until you have tried both, don't be shy of a tall 1st.



On an unrelated note. This is 518 vs NV3500. They soak up alot of power. I did a 518 swap in a truck. While climbing a bridge near me. I had to turn off the overdrive and unlock the converter to climb this bridge in 4rth. When I swapped to the 5 spd manual. At the same rpm I could easily climb the bridge in 5th gear. The same truck had a 3 mph increase in trap speed and 2 mpg improvement.
I am not saying a Silversport 4L60E would be any better than a 518 but after seeing the numbers for me, I'm not a fan of 518. The rpm change seems to be the only thing talked about but poor mileage in Ram1500's make me thing they are not the way to go.

has anyone used a 518 with a manual valve body ? if so, was it a forward or reverse pattern ?
did you buy the valve body or change it over with a kit ?
as always, TIA.

I have a forward manual valve body in my 518. The Hemi wants shifted at 6,800. To get the most out of it, manual shifting was the only real answer. Besides, I didn't want a strong hit going into 2nd and didn't want reverse to bang in with the 850 RPM idle.

I called A & A and they got it right the first time. It works good with the Slap Stick.

how is overdrive engaged? with the manual valve body or through an electrical switch?