The basic B-Body chassis is pretty much the same from the massive redesign in '77 until the end of the line in '96. The wheel hub pattern will be different between the '87 Civi (5 x 4.75")and '92 9C1 (5 x 5"). Your '92 has the heavy duty frame that came standard with the 9C1 package. If the '87 has the F41 package, it may have it too. The transmission crossmember should be the same, assuming the '87 also has a 700R4.
Unless the motor has been replaced the '87 has a 4bbl 305, standard was a TBI 4.3L V6. Only the 9C1 cars got 350s from '80-'92, unless you count the boat-anchor [img]tongue.gif[/img] Olds diesel 350 [img]
The transmission maybe either the 200R4 or the 700R4, look at the tranny pan to be sure. The 700R4 has a retangular pan with one corner slightly clipped.
The rear end will fit the '92, its your call if its worth it though (no ABS, maybe different ratio, drums, etc. on the '87). Ditch the '87s rear control arms. For the price, you're better off buy aftermarket anyway. I think Mike at No Limits is still offering killer prices on BMR units. Unless the '87 was an F41 car, your '92 has the better sway bars. The F41 would have the same as 9C1. The springs will interchange, but again for the price, you're better off buy new GM or aftermarket springs unless the '87 has a really good set.
The front control arms are worth yanking off the '87. Rebuild/overhaul them for installation on the '92. That way you'll have minimal downtime on your '92 [img]smile.gif[/img] You'll still need to use the '92 knuckles to retain your 5 x 5" pattern. Or you could use the '87s front & rear suspension to convert your '92 to 5 x 4.75" and have a larger choice of aftermarket wheels, but you'd lose ABS.
You '92 9C1 has the better quick ratio steering box (12:1 or so). Unless it has been replaced, the '87 has the slower a.k.a grandma steering box (14:1 or so).
The floor pan is about the only part of the body that is the same between the '87 and '92. If the seats are good in the '87, grab 'em. The steering column would be nice to keep around if you need to rebuild one in the future either the '92 or your Mailbu (or just about any other GM or Chrylser for that matter). The pedals should interchage also.
If there is anything else I missed, let me know.