z34 tranny issues

the tranny in my 91 z34 is shot and i was wanting to know if the one out of a ss monte carlo will work with it. and if so is wut would i need to complete the swap.any feed back is appreciated

In 91( I assume it's an automatic because they never offered a Monte SS with a stick) they used a 4t60-E (rpo code M13) exclusively behind the 3.4 DOHC. They could have used a or a 4t60 (ME9) non-electronic 4 speed or a TH125 (MD9) 3 speed auto behind the 3.1. A trans out of a newer (97-up) Monte SS will not work. The trans in your car uses a vacuum modulator for shift control, where the 97-up 4T65-E is fully electronic. Your car's computer doesn't have the ability to control the shift points on a newer trans, so you'll have to stick with one from a similar year car (pre-96). You'll also have to be sure your replacement trans has the same final drive ratio or your speedometer will be off.

the guy at the shop said that it wont plug into the ecm and the bell housing is different so it wont bolt up.he wanted me to pay a grand to rebuild the old one.

...be sure your replacement trans has the same final drive ratio or your speedometer will be off.
The speed pickup is off the right wheel output shaft on the case extension... this is past the final ratio so whatever the ratio, the speed pickup reads the actual wheel speed.
http://www.avigex.ca/xport/4T60pickup.jpg