Just some FYI: TG uses cheaper (specificaly, Chinese) materials, hence the lower price. If you want quality, American-made parts, Marlin Crawler has you covered. The same can't be said for other companies such as TG.
As for gears VS dual cases, it all depends on how much you drive your truck. I lifted my 85, ran 35s (with 4.0 case gears) and 5.29s for the last year. I couldnt have been happier. I already had a pretty low low range but I still got good gas mileage and I had good power on the street. I just went dual cases and it is fantastic. Looking back, I am glad I went with case gears and axle gears BEFORE dual cases, because the dual cases dont do anything for you on the street. If you have big rubber and dual cases you are still going to be hurting on the street. On-pavement performance was important to me because I DD my 4runner, so i went axle gears before dual cases. If its more trail rig than street rig and power and gas mileage arent a concern, duals is a great addition. Just remember the front driveshaft needs to be lengthened (a square shaft is a cheap fix) and the rear needs to be shortened (not so cheap if you want it done right).
As for what gears are right for you.....
Up to 35s - go with 4.88s
35s and Up - go with 5.29s.
I went 5.29s and they are great with my 35s. Going 37s soon and IMO, 5.29s are perfect for a 35 and larger tire. I wouldnt get 5.29s if 35 was the MAX tire size i wanted to run.
