Mine is a '75 GMC and has been in the family since new. My dad had a '74 GMC and I have seen several break in thirty years. I have owned GM's and Dodges with the 205s. If it were to come down to dependability and ease of service I would choose the 205, I have only seen a few of those break, lots of power, torque.  

I have never seen a 203 break that was properly used and serviced. If you do not change oil in that every 12 to 15K or so the chain will wear out sooner and get loose and when that happens it can jump a tooth and break something. In my 79 J20 Qtrac, all of the torque all the time is on chain (unlike half of it in a 203) and it has had a VERY hard life and still original chain. Many never bother to change lube in axles let alone Tcases.  

i have a 78 1/2 ton with np203 lockouts on it. it wont move when in free now i dont care the trucks junk i have the full time hubs in good shape if any one whants to buy them i also have a np20? with 4h 4l 2h 2l for sale now im new this is my first post so let me know  

I recently had the 203 on my '73 K5 rebuilt, and I also installed a Superwinch part-time kit.  I keep the Warn Hubs unlocked and run in 2WD most of the time.  Lock the hubs and drop into 4WD and you're ready to rock.  No problems so far.  

What T-Case parts do you have and for what trans?  

What brand and type of oil should i be putting in this 203.   I can say i abused my 203. i started getting a little ticking noise while going down the road and about 3 weeks ago i was pulling my 4-wheeler trailer about 30 mph. Then the ticking noise got loud as heck. Sounds like a constent slapping of metal agains metal. I stopped the truck and threw it in High loc and the ticking went away. then put it back in H and it started Back with the loud slapping noise. Got to the house and pulled the front drive shaft. Still doing it in H but not as bad in H Loc. Called shop and he said it is the Chain belt.   What u think?   ( keep in mind I have the conversion in the transfer case)