I Don't Know Jack(s) ?

[Ironhorse]

Have owned several of these 67-72 trucks (all 1/2tons) thru the years, one '71 Blazer but none were Suburbans or 3/4 tons. Never have really known, was there a specific jack for the 1/2 ton, the 3/4 tons, the 4WDs and so on or were their various jack vendors supplying GM, both Chevrolet & GMC, with a different jack depending on the factory build location? Have three jacks that have been sitting around for some time, no markings on them that I can find. Have not cranked them all from lowest to the highest setting but all use the folding style jack handle. Did other truck corporations such as Ford, Dodge, IH and such use the same jack vendors? Anyone who can help me know jack(s)? LOL.