Hot Rods 700r4, what should I look for?

Want to get a used 700r4. Remember reading there are some years you should stay away from. Also, I have a mechanical speedo right now. What years will fit the bill for me?

 

The first few years are the ones to avoid unless they have been rebuilt and upgraded. I would say anything from 85-90 would be the best ones.

 

1987 and up will be good.

 

The newer the better. Check the date stamped in the case next to the pan flange.

Also, there are three different tailshaft housings, commonly refered to as F-body, Corvette, and Pickup. I think they're all the same inside, but the difference may be a factor when you bolt yours to your frame.

 

newer the better... The electronic speedo started in 88, you can convert them, usually...not sure how new of ones you can convert though.

 

Look for this rainbow or cam lobe shaped casting mark then check the numbers. It will have a lot of factory upgrades.

 

Some units have a large letter "K" cast into the bellhousing. These are the truck version which apparently have a slightly thicker case / bellhousing.

 

Not seeing it, what rainbow?

 

The red servo cover is in the middle. Looks like a cam lobe.

 

the casting line I outlined in red?

 

Correct.

 

Thanks, sometimes I'm a little thick in the head. This was one to those times.

 

Retracted comment. Found my answer.

 

I used a 88 Camaro in my 35, mechanical speedo with trans mount on bottom of case behind pan. I hung the exhaust off mounts bolted to the old trac rod bosses.( Photo 2, post #4)

In my 46 Olds I used a 90 Corvette and had to change the output shaft and extension housing (Photo 1, post #4) due to trac rod mounting. Trans mount this time around was on new (earlier) extension housing as case was not drilled and tapped for mount, only the boss. Also adapted electronic speedo in lieu of mechanical.

Also make sure you get the correct trans, a 700R (4L60) uses a throttle valve cable, later 4L60E does not, look for the TCC connection as this transmission requires a separate stand alone ECM to work the solenoids unlike the 700. 700R and early 4L60 used a single piece case with 4 x bolt extension housing, the later 4L60E were 2 x piece cases with 6 x bolt extension housing.



Also Corvette 700s had a larger servo. MD8 case and K cases as per photo are heavier casting and more desirable. 1989 I believe was the last year of mechanical (Cable drive) speedometer. 86 and later 700s had the stronger 30 spline output shaft, not the weaker 27 spline shaft.

 

input shaft, not output shaft?

Good info, thanks!

 

You haven't said what engine and what all this is going to be running in.
Remember the TV cable. It's setup is critical to the survival of the 700R4.

 

Oops, typo error in my haste to go to work, sad isn't it.

C4 Corvette extension housing & output shaft -v- conventional extension housing and output shaft. Also note no transmission mounting boss.