Totally new to the site and hoping for a little info on a possible rear end swap. I currently have a stock 84 305 with auto trans and the axle bearings and pinion bearings are toast, or so ive been told. Curious if i should have the current non posi rear end rebuildt or swap with a used setup? Wondering whats compatable and where do I start?

 

axles from 82-2002 are bolt-on-able. beware though 93-02 are 4th gen axles and depending on year are just about 2" wider on each side so the wheels will stick out a little. they don't look horrible (as you can see i like it), but they are a like or hate thing. do a search if you think you might be interested, there are many people on here that have taken pictures. other than that if you stick to a 3rd gen rear axle, you can use a 10 bolt or a 9 bolt (offered in some of the 88?+ cars, slightly stronger supposbably). You can always rebuild your original axle, but thats your decision. Getting a used axle also has it's questionability for how long it'll last.

 

Will the whole rear end bolt right in?
Will the bolt patterns be different and what about the offsets for your rims, is any of that affected?

 

if you are refering to a 4th gen rear axle swap, yes, it will bolt right in, lower control arms, panhard bar, and even the torque arm will all bolt in. Like i said depending on what year it is (4th gen wise), it will stick out roughly 2" for 93-97, or 1.5" for 98-02 give or take. Brakes will also be different, 93-97 have i think 11.5" rear discs if equipped, and 98-02 have 12" PBR disc brake setup identical to the LS1 brake system. I was using my 15" 1988 base model cross laced wheels and it cleared the massive 12" rotors of the 1999 cars. It rubbed every so slightly that i might have had to grind down the rotors slightly, but then i got hooked up with a really nice set of 16" formula wheels, so i didn't have to do anything. 3rd gen wheels will bolt right up, only issues that i know of are the GTA 16" crosslace wheels will not clear the caliper without a spacer i believe. Other than that i believe that the offset of the stock wheels should pretty much fit. Really if you can find a donor car local to you bring your wheel with you can check. Remember that if you have 15s (which i know in 84 you do), that you need to accomidate a hot caliper (as it will expand). just some things to think about. People have gotten by with 15" wheels, although 16" would be the easiest swap to go to and maintain an almost stock appearance. As you can see from my signature, i have the 1999, which sets my stock wheels out 1.5" on each side roughly, and the stance from the back looks absolutely sick. I think well worth it. Again, up to personal preferance though.

 

Thanks for the info, as for the wheels, ive currently got 18 inch wheels on the car so spacing is not a concern. Going to the brake size, do i need to change anything on its set up? Dont rear disk operate on different amount of pressure than my current drums?

 

yes, you either can take the simpler route (more costly) and get an adjustable prop valve and put that inline with the rear brakes off of the master cylinder, or you can use a 4 disc (RPO: J65) proportioning valve (weird looking thing under the master cylinder/container). It has 2 lines going into it from the master cylinder, and 3 lines going to the rest of the car. I'm not positive if your 84 has the newer style or the 82/83 style prop valve. You may need to move some lines around, but all together, it's been agreed that the 1989+ prop valves are the most appropriate stock looking prop valve to use to do in that time era they were using 11.5" rear rotors, so 12" isn't much of a jump. Although if you get an adjustable prop valve, then you can control the rear brakes independant of the fronts to have complete control over lock up point and brake distrobution control.