87 B2600i rear differential fit in a 1990 B2600i?
 

Hi,
I have a 1990 mazda b2600i, 4x4, 5spd with 248K miles and the rear end just went out. The truck has a 4.30 rear gear ratio for the rear differential. I found a rear differential assembly for a 1987 B2600 4x4 with an automatic transmission. The ratio for this set is 4.10. Will the 1987 assembly bolt into the 1990 rear housing? Seems it is hard to find rear end parts for these trucks. Any help/ideas on this would be great and thanks.

gear ratio has to match the front or 4wd operation will chew it to pieces.