98 Gmc 4L60E troubles

[Adam snapp]

New to the forums, needing some help here, recently bought a 98 GMC K1500 Sierra SLT ext cab, 5.7L vortec. Have been chasing a gremlin with the trans so far, I know the Neutral Safety switch needs to be replaced as it doesn’t start in park only in neutral, kid I got it from said he burnt the clutch packs out for 3-4 gears however I’ve not seen any sign in the pan or smelled burnt fluid or clutches. Truck will start out in what feels like 1st and then have to rev rpm to about 3 grand to shift into what I believe is second or third. Top speed is about 50 at around 2300-2500 rpm and no other gear shifts. Speedo works, as well as other gauges (I’m sure they’re not reading right) ABS light on, brake light on here and there, no Check engine light on. Also when shifting from N to D trans slams in to gear as if 4x4 was engaged but it’s not as i have the front driveshaft out and tested before hand to make sure it wasn’t stuck in 4x4. Ive read and watched countless things on what it could be and gotten no where. Trying to narrow down the source of this pain in my a$$, any help is much appreciated!

 

[Ledzep]

Does it have reverse and a whine from trani? If reverse is ok and no whine, start with Adjust neutral safety switch 1st, block wheels and/or parking brake on, key on engine off, put in reverse and have someone whatch reverse lights, when rev light on, lock the 2 13mm nuts down. Make sure transfer case is in 2hi, just because you have front driveshaft out does not mean transfer case is not in 4wd.

 

[Adam snapp]

It has reverse but barely, engages extremely slow into reverse and have to keep pedal pushed so it doesn’t bog out. No whining or clutter or banging except when going from N to D or from R to D it slams in gear. I will make a short video tomorrow and see if I can’t upload it here. How do you be certain it’s in 2hi not 4x4 besides seeing if the t case is rotating out to the front?