I just finished up an install of an 8.8 diff in my project vehicle and would like to toss out a couple things that I learned that will save you some time and money.
First of all the 8.8 from under an Explorer is a tough over-built unit. Not quite as tough as the 9" but said to be stouter than the 8". 31 spline axles and higher number R&P ratios make them attractive to those adding OD transmissions to their machines. The axle tubes on the 8.8 are 3.25" in diameter so you want to salvage the u-bolts and lower mount plates as well as the rear universal flange mount plate from the donor vehicle. Most over-the-counter U-bolts are 3" max and custom u-bolts can get pricey. Also, the emergency brake setup combines both cables into a single cable which would make adapting it to the stock AD E-brake mechanism much simpler. Also keep the rear u-joint attachment bolts....they're metric and $2.00 each from the dealers!! The bolt pattern on an 8.8 is 5 on 4.5.....not the usual GM 5 on 4.75.
The pre-95 diffs are 10" drums and the post-94's are discs. The axle code is on a sticker on the drivers door post:
#44 is a non-locker 3.73
#45 is a non-locker 3.55
D4 and D5 are 3.73 with traction lock.
I was pleasantly surprised at the number of diffs, both drum and discs in our local yards. You didn't have to crawl under the vehicle to hunt for a tag to ID the ratio, and that the biggest surprise was that my yard charged me a flat $100.00 for the 3.73 drum Trac-lok. I could have had a disc setup for the same money.
The current lists of donor diffs has you scrounging for 35-50 year old diffs that are at least going to need all new seals and brakes if not bearings and gear sets, if you can find one!!!!. It might be wise to consider taking a closer look at the 8.8 and keeping a little of that extra jingle in your own pocket.
Dave
