Hey guys,

I'm about to send my transmission off to be rebuilt, the kit came from Dana at Pro-built. My question is, the new transmission is an 88 700R with provisions for an electronic speedo...it also wasn't out of an F-body car. Can I simply swap the tail housing from my 84 model, complete with mechanical speedo gears onto the newer tranmission or will there be more work involved?

 

You'll have to swap the tailshaft housing anyway if you need the stock torque arm mount. Otherwise the electronic sender and mechanical sender pretty much interchange. You may have to swap the internal speedo gears, if they are different.

Before swapping tailshaft housings, be sure to install a new bushing and seal in your 84 tail (or stick your housing on the tranny before sending it off).

 

The car is my DD, so I was going to try and do it over a weekend, and do the tailshaft/housing after the rebuild is done but it's starting to look more involved.

Can the tailshaft be swapped after the rebuild or does it need to be done while the rebuild is happening?

 

Swap it out after the rebuild, no problem. Just keep the seals needed for the tailshaft housing and install them before swapping. Should have a large o-ring for the tailshaft housing to tranny, small o-ring for the speedo cable input, o-ring for the speedo housing, rear yoke seal and bushing. I may be missing one?

Pull off the 88 tailshaft housing and you should be able to identify all the needed seals except for the speedo cable input.

When you get the rebuilt one back you'll have to check the speedo drive gear, which is installed on the output shaft. Make sure it's the same as your existing one. If not you can swap them over easily.

 

Outstanding! Thank you for this. I'll be sending it out early next week for the rebuild.