'99 NP246 in '04 suburban (NP246 problems)
 

Hey guys lost 4wd this weekend. It worked Friday, it doesn't as of today (Sunday). Just recently swapped the 5.3 with a mildly built lq9. At this point I know for sure t case is shifting to 4high, 4low, 2high. Not sure about auto 4wd but according to the light on the push button it is. I can hear the t case motor doing its work when under truck, and positive I'm in 4low when button is pressed, I've pulled the actuator off the front diff and I know this works as should, swapped out a new pre programmed TCCM. Changed fluid about a month ago with auto track II. Looked as it was fresh (only owned truck for 2 months) if I'm shifting into the 4 different settings does that rule out the t case electrical issue and narrow this down to the clutches? I've found a few was to check 4wd engagement with spinning wheels and jacking truck up. I'll try them tomorrow and see where that gets me. Any thoughts would be great!

Second I have a '99 4l80e with its mated from factory t case (np246). Trans will be going in soon and if my t case is shot, what will I have to do to get the '99 NP246 working in my '04 truck? I'm finding out there are some slight differences. Will I be able to complete the t case swap? I'm not worried about any driveline issues I can figure those out but electrical issues, harness clips, sensors, motors.. all that crap. What do I need to be looking for? Any help would be appreciated! THX!

Are you sure its a 246 on the 80e? The 246 is a half ton case, and the 80e is a 3/4t + trans. Except the 1500HD, but thats really a 2500 with badges.

Anyway, point is, I dont think you have a 246 on the 80e because I dont think the 246 was available 32 spline OEM.

That being said, I would 10/10 consider the swap to a 261 manual case and fuck all that auto shit. The wiring and everything will be the same as for the 241 swap, if you want to look that up.

Much better t case, no clutch to eat shit, and no pump to rub.

Positive it's a 246. I was surprised my self when I seen it.. it came with the trans. Must have been a 1500HD. I'm considering what you mentioned too. Fortunately I just found out today the t case isn't my problem and it's the front diff so the urgency isn't there but the 80e is sitting on my garage floor for a reason and I'm hoping to get that in before I destroy the 60e. It's already showing signs of old age. With that being said I wouldn't have to buy any adapters or different input shafts to take care of the 80e swap as I've got the set up ready to go. Only problem is I'm seeing the encoder motors are different. I'm thinking I may be able to get the TCCM module from same generation and encoder motor harness and splice it it. Was hoping to gain some light before I dug in and did it the good old fashioned way. i suppose I'll have to get under the truck snap a pic of the connector and go from there maybe call a Gm dealer about the TCCM issues unless someone chimes in. Knowing now that the t case repair isn't as urgent, I should consider getting rid of the auto trac when I'm swapping the 60e for the 80e. I'd assume a 3/4 ton 241? or 243? Should fit with the obvious crossmember mod and needed driveline changes? 243 is push button correct 241 floor shift?

Looks like I had that backwards. Just getting familiar with 4x4 shit. Always had 2wd. Seams like the 261 would be the money shot. I'll have to do some more research on that. I'm all for doing what I can to strengthen the drive train up. I was breaking shit with my RCLB 2wd. I'm smart enough this time around to know I can't beat the suburban until I deal with some of these weak links starting with the trans. Was digging left and right for reads on swapping out a 3/4 ton front diff in my 1500 burb but it seams as tho it's too much work for too little reward. Solid axle seams the only reasonable soulition when time, money and overall usefulness is considered.