Hello, since it looks like I'll never get a Passon 855. I might have to go with the OD 4 speed. It will be behind a 470 roughly 550 hp 570 torque. Anyone running one of these? Opinions? Cruising RPM with your gear ratio, tire size? Thanks in advance.

I have one in my challenger, really like the difference it made. I replaced a good 18spline with it, and the reduction in highway cruising rpm made my car much more enjoyable. Rpm at 75 mph dropped from 3450 to 2750. Gear ratio spread between the gears feels much better than the factory OD with it's "granny" gear first (ran one of those a while). Other than a being little more "gear noisy" than the 18 spline, it's way better. Hoping this is only due to "break in", though I do have a couple thousand miles on it now. Good gear ratio, speed RPM calculator here: https://www.crawlpedia.com/rpm_gear_calculator.htm

I have one in my RR. 354 gears and G60x15 tires, 2,500 gives me around 75. If you plan on driving your car any on the Inter State then I'd do it, around town, maybe not. You're not going to any racing with just a three speed, and it's not a slick shift, ie speed shift racing. I have a 528, so I can just torque around town in 3rd gear with no problems. Bottom line, make the choice according to your intended usage.

I've been tempted to do the OD thing, but always wondered about the ratio spread.
I always come back to thinking 5-speed, but jeez, that Passon's spendy & hard to get, and I don't want to cut the car up for the alternatives.

I have one in my AAR gear ratios work for me but its almost embarrassing noisy and they cant seem to fix it. I may just go back to the original gear set and change the rear end ratio

We installed one n my friend's 71 Cuda with a 572 Hemi and 3.73 gears. It works great, just use 3 gears in the quarter with most setups. I think it's the perfect setup with a stroker, I wouldn't want the 5 speed. It wouldn't work as well with a small engine of course.

How about keeping your factory trans and adding a Gear Vendors?

Passon OD is cheaper than a Gearvendors and everything bolts in (driveshaft etc.).

True, but then you have a 5 sp

I tried the Keisler perfect fit 5sp guess what I would have to cut my floor and would still have driveline angle issues. Their solution add spacers between the k-frame and frame rails or cut the torsion bar mount. Ya right on an AAR. Fortunately I got my money back on that one. Next up the Passons OD bolts up fine ratios work well with my 3.91s. Now the catch it sounds like an old truck loosing its bearings. Passons couldn't fix it. The designer couldn't even fix it although he tried harder than Passons This whole project has been years of the car setting My trans has more travel miles than my car has since the resto . Now I have some money in this trans project and no results. Gear vendors might be great but more money. It might be time to cut the losses and go with something the works

I’ve built and installed two. One customer drives his with a 3.54 and loves it drops the rpm to 2700 or so at highway speeds. He does not complain about the noise but his car is not that quiet. The other guy did mention the gear noise but his rear end makes noise as well. I told him that it sounded just like most hemi boxes anyway. I will be changing his rear gears so I guess we’ll see about that more.

My car has a complete 2.5 inch Accurate Exhaust system with stainless factory style challenger tips. It is quite and comfortable so the gear noise is noticeable, and it isn't as noticeable in 3rd (which is of course straight through). As I previously mentioned maybe it will quieten down with more miles. The hemi box I removed was quieter, but who knows how many thousands of miles it has on it? Just my .02 and experience so far . jess

We didn't notice any trans noise in this one but everything else is noisey too/

Just the fact that that you have a 470 tells me you want more than to just drive around.
If gear ratio spread is at all a factor to you l, consider a close ratio T56 Magnum. It has minimum rpm drop between shift and is the best shifting manual transmission out there.