700R4 tranmissoion

Have an 85 700R4 out of 85 Camero with mechanical odometer
Want to put in 88 Silverado with 700R4 that has 3rd & 4th gear not
engaging. Can the tail piece of the 88 which has a connector for
digital odometer etc be exchanged with the tail piece of the 85 to convert?
I so how big a problem to do? THANKS

Well, if the Silverado's trans is like the later 3rd gen's then you don't even have to swap tail housings. The VSS just sits in the place where the speedo drive gear is. You may have to pull tail housings to swap te drive gear on the tail shaft though.
Other than that, yes, the tail housings should swap no problem.

the camaro trans tailhousing will have thru bolt holes for the torque arm, but that probably won't matter.