[hatzie]

Originally Posted by 1976gmc20

I thought the 203 low range was a lower ratio than a 205 low range?

Though it's hard to imagine needing anything lower than an SM465 granny and NP205 low range. The first and reverse in my 89 K1500 5 speed is so fast that I use the low range (241?) around close places even not needing 4wd. But my old 2wd 76 with the SM465 would do just fine until I had to climb or more often back up a steep slippery hill. Seems like the 465 granny/reverse is just about as low as low range and 1st/reverse in my 5 speed (3500?).

I had a 91 Suburban with apparently the 208 and never had any problems with the t/c but I also never pulled stumps and semi trucks like I did with my old 205 pickups

The NP203 & NP205 are roughly the same ratio in low range 1.96:1 IIRC.
You can get 3.6:1 gear sets for the NP203 range box. Or just run a NP241.
The thing that killed more than a few of the 208/241 boxes was leaving out the brace between the transfer case and the engine.

The 89, if stock, would've had one of the less reliable Getrag forefathers of the NV3500. I've forgotten what they were called, HM290 maybe??? IMHO The 1st & reverse ratios in those gearboxes were more suited to an automobile than a pickup truck. They work OK within their limitations. The 300ft-lb limit was fine in a V6 S/T 10/15 truck but it had no business in a fullsize truck if you intended to tow with it. I've broken a couple of them towing in early 1/2 ton T400 trucks.