I want the seatbelt setup from the 88. the feel of the 90 SI with the mechanism in the door is different. I also like the way the 88 hold you in better. Is it possible??

 

it would be a huge PITA, not worth it IMO. You'd need the rear interior 1/4 panels from the 88, along with the seatbelt assemblies, and door panels, and you'd probably have to do some custom work to make everything fit.

 

Its entirely possible. all of the 90-91 b pillars have holes pre drilled to mount the 88-89 seatbelts. You will have to weld in a few minor things. take a look at your 90-91 b pillar vs your 88-89. you'll instantly see what you need and its not much.

 

Thanks! I have a donor car so that will make this a simple process. So the issues are small and will require only light welding. I assume a set of nuts in the B pillar. the 88 doors are alot lighter and i just like to be able to cinch down the lap belt. You can't do that with the 90-91 setup.

 

I had a 90 si shell that had a 88-89 door on one side. The shell was a pos, later trashed.
88-89 doors do fit, but the only snag are the black support things in the 90-91 door jams towards the top of the jams.
They will come out, but only with a bunch of beating or some nice power tool.