I was driving my '87 4.9L, 4 spd, 4.11 gear, 4wd today on the interstate and decided I need a lower gear ratio for highway driving, which is what I do the most of. I want to keep my current rearend and was thinking of finding donor with either 3.08 or 3.50 gears, preferrably with limited slip. I know that I can't mix gear ratios between front and back, but I rarely use 4wd so I can control that. I'm currently running 2500 rpms at 55 mph.

So heres my question(s)
1. What year trucks could I get a donor from?
2. Are all the truck 8.8 the same width, bolt pattern, backspacing?
3. Is this just an unbolt the current and bolt in the donor?
4. What kind of rpms would I run at 55 mph with either gear ratio?
5. If the donor has disk brakes (mine has drums) what would be required to make the disk brakes work?

I want to make this as simple as possible, assuming I can find a good donor at a reasonable price.

Thanks,

Chris

 

I did a axle swap on my 89 f150 4.9 with a mazda 5speed. I think you have to swap out front if you do the rear. I think the axles would be just a straight swap. I got mine new axles from a 89 bronco. I went from 3.08 to 3.55s. If you are looking for a truck that has 3.08s the axle code is 18.
Here are the rmps with the 3.08s. This is all in 5th. 55 1600rpm. 65 2000rpm. 75 2300rpm almost 2400rpm.
I run 31x10.5 on 15in rims and when I changed my gears to 3.55s I got better mpgs.
I have my rear axle at my house right now for sale. I don't remember if it is limited slip.