I bought a non running 73 Grabber with a 86 Mustang 302 and a T-5. There are several issues I am still scoping out including what to do about the rear end. The car originally came with a 250 cid motor and a stock 2.79 rear end. I suspect that with the T-5 I will need to go to at least a 3.50 ratio. What are my options? Can different gears be found for the rear end or do I need to look for a 9 inch. I'm interested more in simplicity over cost (up to a point). What can be done with the existing rear end? Are there 9 inch options that don't include cutting and welding? Is there an aftermorket rear end that would bolt right up (likely no)?
You can get a complete center section with a good selection of ratios. Replacing the center section is pretty simple. While you're changing it, I'd consider getting a center section with Traction Loc. Check ebaymotors or a local shop that rebuilds rear ends or contact user bryant here on mmb.maverick.to.
depends on what are your intentions for this ride? If it's an econo crusier.. slash.. occassional bruiser?.. then there are couple of things to consider even though the 8.5 rearend is only considered good for medium duty without bigger cash being poured into it. 1st gear ratio is very short in the T5 so you don't need a short rearend gear to get off the line unless you want to lift the front end and shift at 20mph(a bit dramatic.. but you get the point, I'm sure). the car is very light.. so you don't need as much gear to do the job. you have an overdrive now so even if you do go too short for gear?.. you can get by just fine for highway rpm.. but gas ain't gettin' any cheaper either, so there's that. you'll usually need a bit more cam to make better use of a T5/3.5 rear combo's higher rpm band. Maybe at least around 220'ish duration at 50 thou.. which of course brings out the flow restrictions in the heads(some of which are downright terrible) and intake package as the next weak link. Without knowing the intent it's tough to say.. but I would probably recommend looking at 3.25 gears for all around fun and decent cruising. Need to figure where you want the car to end up before you throw too much cash into an 8.5. There are tons of aftermarket parts for these rearends but when you want to eventually get serious about rpm/power?.. a 9 inch will get you there quicker and cheaper in the long run since it starts at around 25% stronger(even more in some area's) right from the stock baseline.
