91 suburban 1/2 ton come with 56" springs?

[moturbopar]

Hi all. I am getting ready to do a shackle flip on my suburban, and am wondering if the 56" rear springs on my suburban are factory? I was going to replace them with some 3/4 ton springs but these are in great shape. so these are factory right? when did they start putting them on 1/2 ton suburbans?
Thanks

 

[dleroy43]

I have an 89 it came with 5 leaf 56s. I replaced them a few months ago wit 8 leaf 3/4T springs couse my 5 leafs really sagged

 

[resurrected_jimmy]

I had a 91 burb with factory 56" rears, when I bought my lift for it I know you had to specify which rear springs so I would guess chevy had been doing it that way for a while

 

[moturbopar]

Thanks for the replies!