Interesting!
Did some looking and your RPO code "GQ1" means the standard axle ratio given the engine/tranny/and federal or CA for that year. So, not really easy to tell unless you take the cover off.
Looking at this chart (pdf) and your tranny (MX1), looks like 4.10.... page 6.
https://www.gmheritagecenter.com/doc...t-Suburban.pdf
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- Jeff
89' K5 Blazer, 2.5" lift, 35" tires
04' GMC Yukon XL, 3/4 ton, 8.1L