Whats very coincidental is those suburbans in the article are on the Wikipedia page for that generation: https://en.wikipedia.org/wiki/Chevrolet_Suburban#Sixth_gener...
> The highest gear is third gear.
Was it the strait 3 speed or the 4 speed with a "granny gear" aka the stump pulling L - Low range? 4 speed should be the Muncie SM465 which I had in a GMC 6000.