Your not kidding about expensive, the last one I saw was around $600. I enjoy my three on the tree so I decided to keep it. The T85 will be a good trans for you. I first used one in 1969 in a 57 because I kept blowing the light duty three speeds.
The current T85 I have I traded a 4 speed top loader for, I love the OD..

I have been running 12 volts for a long time - quite a bit on my blog at 1955 Ford Blog | hotrodreverend if you ever have time to visit. Finding that Hurst kit was not easy and certainly not cheap, but I am thrilled to have it. I think most guys go with either that 4 speed or a modern 5 speed option. I like the operation of the Borg Warner OD units and since I am building up a very strong 312 I need to go the beefier T85 route.





Daniel Jessup

Lancaster, California

aka "The Hot Rod Reverend"
check out the 1955 Ford Fairlane build at www.hotrodreverend.com

The driveshaft yolk is also the same as the large output Toploader 4 speed. I was able to use the one from my old T85 when I put the large output toploader in my 57 T Bird. 

I saw those - that Mercury setup is a different bird for sure, thank you




Daniel Jessup

Lancaster, California

aka "The Hot Rod Reverend"
check out the 1955 Ford Fairlane build at www.hotrodreverend.com

Daniel  I sent you a couple pictures to your e mail    Carl

A Hurst for the t85 is a super bonus, they are almost impossible to find these days. Is you 55 been changed to 12V ? The T85 will have a 12V solenoid.

Thanks fellas, I should have posted more... My 55 is currently running the 3 speed R10 transmission and I do enjoy it. Also, I do indeed have the yoke that was installed on the T85 from the factory, and this T85 was removed from a 1957 Thunderbird. From all accounts, it has the same case and spacing as a 56 Mercury or HD 56 Ford T85. 10 splines on the snout, etc. If I can get some photos that would be nice. I do wonder if the transmission will need to mocked up first, the cross member marked for the extra holes, or if I can modify the existing cross member before getting into all of that. Is there anything else I need in the way of mounting hardware? As a bonus, I do have an NORS Hurst Syncro-loc kit to install for this T85 - it is R11 specific as well.

Daniel Jessup

Lancaster, California

aka "The Hot Rod Reverend"
check out the 1955 Ford Fairlane build at www.hotrodreverend.com

My last T85 swap into my 57 I learned something from the drive shaft shop owner, the rear yoke is the same one they used on C6 autos in later years.. I wasn't aware of different mount on the tail shaft, my was a bolt in with no problem, the T85 was from a 1961 Galaxie and I needed to change clutch disc to a 23 spline.

I did this swap several years ago in my wagon. I'm working from memory but, I retained the stock crossmember and just fabricated a extention for the trans mount. It's been in there at least 5 years with no issues. When I get a chance I can get you some pictures.

Durham Missouri

Dan,
I'm going to be making the same swap within a month or so.  I rebuilt my T-85 and will be installing it in my 56 Victoria hardtop.  I have not looked at the cross member (car has an FM in it), but I'm pretty sure what's in there won't work as the T-86 is shorter than than the T-85.  Also be aware there are at least two rear housings for the T-85, one had the mount forward and the other was set back 5 inches as well as length differences. 
You're going to need a T-85 yoke if you don't have one, T-86 shaft's are too small diameter.  Used ones are getting tough to find.  You're probably aware of it, but you will need some electrical bits, relay, circuit breaker, kickdown switch, and the In/Out cable.  If you already have an OD you're set up.
I have some rear housing dimensions and drawings, but my shop computer is inop, but I could have it back by tomorrow if you need more info.
I had never heard about the PI 312 using a T-85, but it sounds likely.   
Don