np246 banging in 4wd

New here so bear with me. I had my 4L60E replaced now when I put it in 4 hi or 4 low it sounds like either the chain is hopping or splines are skipping as soon as ther is any torque on the ft end? 4wd lights all stay solid hi or low, just the noise is terrible and had no problems prior. Note they couldnt get the front prop shaft out of the t-case when doing the trans so they took unbolted it at the diff and left it attached. Could this have jarred somthing trying to remove it from the t-case? The pump has not worn through the rear cover and fluid level is norm. I only attemted to use it twice for a couple seconds. Any ideas before i replace or pull it and open it up? Shift motor? Lights dont flash on dash tho.

Are you going 4hi then 4lo? How fast are you going when you grab for 4lo?

Shifting from a stand still in neutral. Engages normal in either hi or low, light stays solid. When I accelerate it skips. I have been hearing a bit of writing noise from the front end but I believe it's the left front wheel bearing as it does go away when I turn and the weight comes off of it. Could it be from the front diff?

Im thinking its not that they couldnt get it out, they just didnt want to pull the exhaust in order to do it right.
Did this problem develop immediatly after you got it back?
The front shaft is a "slip joint" if that joint is worn it can bang as it turns.
Give it a coat of cheap white paint paint and put it in gear for a couple of turns.
Get under and look for wear marks.
Make sure they actually put the bolts into the crossmember and tightened them.
Make sure thdy didnt whack your trans mount bolts with an impact and pull the threads out of the case or break the mounting block off ( real common )
Hell, for that matter, make sure they put the crossmember back in
I guess its possible that your new found torque skipped the chain.
But I Really, Really ,Really doubt it
Pull the fill plug and stick a screwdriver into the chain and kinda move it around to look for slop.
Dont stick your finger in there unless you dont need it.
Drain it and look for sparkley glitter in the fluid.
But first, go into the lobby of whatever fly by night ********* that had the audacity to rebuild a 4x4 transmission without insisting that they also diagnose the transfer case and driveline before giving you a quote.
And didnt road test the whole system before they sent it back to you.
It could be all random circumstance.
However, I would much more willing to believe that, were it not for the fact that they were either too friggen lazy or stupid to bother googling how to remove the damn drive shaft.
Its not rocket surgery
I hope you got some kind of a warranty.
Dont take any **** off em either.

Thanx, I'll check into the slip joint further. maybe with the fighting to try and get it out it didn't get put back in all the way due to it being seized up a bit?? The shop and tech are legit and I know them well. A cooler line had blown off my trans on the highway and I cooked it that's why it was getting replaced. I've asked for his input as well.

So guys n gals, it looks like the previous owner swapped the front prop shaft to a solid (non-slipjoint) style. Its in the t-case all the way and I checked with the tech, he said he didn't bother fighting with it when it didnt come out easily he just unbolted it and took it off from the front diff. dropping the trans/t-case assy. together then seperated the trans off of it on the floor. Could the front diff actuator cause such a racket if its not engaging the hubs all the way? I saw a video on you tube on removing/testing it thought that would be my next step before giving up and taking it in for a proper diag. I dont want to swap in a used t-case if I dont have to ($400) or partial rebuild it myself ($600).

If some one put a solid front drive shaft in the front there is a good chance that the T case is toast. The front suspension moving up and down during normal operation will pull on the front bearing/bearing retainer with a solid drive shaft causing excessive wear. Another possibility is that the front pinion bearing is toast or the front diff housing is damaged.

Any repair tech that is "legit" would have brought the solid shaft to your attention BEFORE they returned it to you.

Just in case there is a little confusion here, an NP246 does use a solid front drive shaft and the yoke is a slip yoke. There should be a boot at the point where the driveshaft goes into the t-case which is where the splines are. This point is intended to remain lubricated with grease so it can slide in and out like the yoke for the rear driveshaft. The front driveshaft has the male splines and the t-case has the female splines if that makes sense - pretty much the opposite of the rear driveshaft yoke. It should definitely slide in and out so you do have a problem if that is not happening.

Correct me if I'm wrong. On a IFS isn't the front diff fixed in place same as the t-case? Only the CV axles should articulate. The only movement would be the minor torque movement on the t-case. A solid front shaft should still be ok.

You are right that there is not a large amount of movement between the front diff and transfer case like you would see with the rear axle, but it is enough that you need to have some sort of slip yoke. You will find a lot of 241/243 front driveshafts have worn splines with a little slop which is a result of wear that you would not get if the shaft never compressed/extended. You have movement of the engine/trans/t-case, frame flex, and slight movement of the diff which can be in different directions. The lack of a slip yoke will put a lot of stress on the transfer case and differential that could lead to damage.