GMC Models - are they Jimmy , Sierra , High Sierra? Or are they all Jimmy's?

How can you determine what model you have if it has been de-badged?

What options did each model have that were different from each other?

Mine ( 1979 ) has manual windows so I presume that counts out the High Sierra.

High Sierra for the Jimmy started in 75, which was a change over from Sierra, which was the deluxe trim package for 73-74; however, there were a few leftover "orphan" 75's that recieved the leftover Sierra trim, and mine is one of them. High Sierra continued as a trim package through the late seventies (about 80ish it switched to Sierra Classic), and your trim package would be listed (usually) on the RPO sticker in the dash. High Sierra would include the rear quarter badges and passenger side dash front panel that said 'High Sierra', and deluxe interior trim. It was basically just a trim package, didnt have any bearing on driveline features. Again most of what you need to know about your truck would be on the RPO stick in your glovebox. Also, the front fender "Jimmy" emblems on the 73-74 were different than the 75 and later ones.

And just because yours has roll up windows would not count it out as a candidate for a deluxe trim package.

SLIMJIM

Roll-ups are standard on any model,as said.I have a`90 Blazer/Silverado with roll-ups.By the 80s most Jimmys & Blazers were "full-dress" with all the bells`n`whistles.Allplastic door panels/no pouches is a good indication of a base model along with single headlights.Although the dual headlight front could be ordered individually.

Jimmy is the model name of GMC's SUV. Sierra, High Sierra, Sierra Grande, Sierra Classic are Trim levels, not models. They way you can tell (if it is still there is look for the trim code in teh glove box. It is hit or miss on these because almost any option could be ordered with any trim level.

See here for more info: http://www.73-87.com/7387info/7387trimlev.htm