I know the 3.9 isn't among the popular motors of our time, but I have a 1990 3.9 5 speed setup in my 48 Plymouth coupe.

My 3.9 is getting a bit tired after 140K hard miles between it life in the Dakota and its life in my coupe. My coupe is using everything from the 90 in it.

I have picked up a 91 Dakota (got the whole truck) with a well cared for 118 miles (before the wreck) with a 3.9 auto.
The questions are:
1) Am I going to have any issues between the 90 and the 91 as far as computer operation? The 91 has a tach, which would be a nice addition to my 5 speed car, but I assume I need to keep using the 5 speed computer (which doesn't have a tach). Don't suppose I can just swap in the tack equipped instrument cluster in place of the non-tach instrument cluster and have a functioning unit, eh?

2) Do all 3.9s have the crank drilled for the stick stuff, or am I going to have issues swapping my 5 speed stuff from the 90 motor onto the 91 motor, both motors are pre-Magnum.

The 91 is really screwed up, it hit a bridge barrier with the right front, then slid across the road and got the railing on the other side with the right rear corner. The truck has a nice bow in it, the right side looks to have a few inches shorter wheel base the the left side. The guy did drive the truck 5 miles home. Rad is still holding antifreeze. I'm going to pull off the sheet metal, but I suspect the frame is bowed, I know the body is sure distorted. Got the truck for $275 with the title.

You guys think I'm going to have any issues swapping the 5 speed to the automatic motor?
Gene

You should be good to go. the computer will work fine on either engine. The intrument cluster should be plug and play also. Im pretty sure the tach wire is already pre-wired so it should work. The stick will go right behind the 91, just bolt on your clutch and flywheel and install a pilot bushing in the crank. Use the one that drives into the larger part of the crank and has the pilot bearing inside it. No crank drilling necessary.

Thanks, you made my day!

Should have the "new" ride home this Sat. Not sure when the motor swap will happen, but I'll probably step up the abuse on the current one, you know, just for fun.
Gene