Suburban axle differences

[Tonyorlo]

I have a 89 k2500 with 3.73s. The previous owner welded up the spider gears to use the axle in a demo derby car.

I have access to a mid 90s suburban k2500 with 4.10s. I would like to use the axle and front diff under my 89 truck. I was told by a junkyard that it would not interchange according to their books.

The trucks are not side by side for me to compare. I have measured inside of leaf to inside leaf at the axle and they are the same(within a quarter of an inch). The outside track from tire to tire is the same, within a 1/2 inch. Tires may be playing a factor in that. Both have relatively stock tires.

Any help on why the axles would not interchange?

 

[Project400]

Should interchange

My guess is a mix up on their part because of the crossover years between square body and gmt400
88-91 pickups were gmt400 except the 3500's
88-91 suburban was the previous generation or "square body"

I'll bet when they looked it up they looked up if an 89 suburban axle would swap into a mid 90's truck. It wouldn't if that's the case