Tell the difference between gm4 gm8 turbo?

[Govt issue]

I was wanting to know if my truck came with the gm4 or gm8 turbo, also how do i know if my injector pump has ever been replaced? 96 K2500 burb 4*4 230000 miles all stock. timing 1.7 vin f

[gmctd]

'96 most likely has the GM-5, with all the improvements over the -4.

It's stamped into the label casting.

[john8662]

To check if it's had an injection pump installed (under warranty that is) you can call your local GM dealer and have them run the VIN of your truck. Warranty repair information is saved by GM, and will reveal how many pumps have been on the engine that were replaced by GM. Otherwise, you'll never know, besides a rebuild sticker on the pump, etc.

[Govt issue]

I looked and my truck has a gm-5 turbo. is this a good turbo. Are there any mods possible. The reason i ask is because the inpeller will move up and down a little. I guess i need to replace it. Any upgrades. Is one turbo better than another where can i buy parts?

[gmctd]

The full floating bearings allow what seems like excessive play when the turbo is cold and the oil has drained from around the shaft and bearings.

Warm it up to op temps, shut it down, remove the inlet duct, and check again - the wheel should not touch the housing at any point, up, down, left, right, in\out.

GM-8 got longer wg shaft\bushing, due to early failures in that area in the -5.

Otherwise identical, and the exhaust housing can be changed to get the improved wg assembly.

[Govt issue]

who can modify the exhaust houseing, and what is a wg?

[gmctd]

Install the -8 exhaust elbow to get the improved wastegate shaft and bushing