S-10 4WD question long

Well folks here is my story. The truck is a 96 S-10 4.3L 4dr Blazer with 138,000 miles. I left on a 850 mile trip pulling a trailer and at about 300 miles I pulled off the slab for gas and when I slowed down I heard a noise which sounded like I was driving over those "wake up grooves". I got gas and was directed to a repair shop to check it out. It was late in the day but these nice guys in Hartland VT. took a look and the one mechanic said he knew the problem. They stayed late and because the parts weren't available they removed the sliding collar gear in the front differential. He claimed it needed a new set of thrust washers and maybe a gear. Bottom line is no more noise and no 4WD. But it's June and I won't need it till Nov. where I am. The rest of the trip went fine and when I got back I read here and checked my Haynes, the Haynes is use less IMO. So what do I order ? And does this sound like that was the problem or is something else a miss? My truck is a three button and I guess has a 233 transfer case. Any help would really be appreciated as all I know about 4wd is the workings of my 67 Dodge M37 which is all mechanical with lock out hubs.

Well folks here is my story. The truck is a 96 S-10 4.3L 4dr Blazer with 138,000 miles. I left on a 850 mile trip pulling a trailer and at about 300 miles I pulled off the slab for gas and when I slowed down I heard a noise which sounded like I was driving over those "wake up grooves". I got gas and was directed to a repair shop to check it out. It was late in the day but these nice guys in Hartland VT. took a look and the one mechanic said he knew the problem. They stayed late and because the parts weren't available they removed the sliding collar gear in the front differential. He claimed it needed a new set of thrust washers and maybe a gear. Bottom line is no more noise and no 4WD. But it's June and I won't need it till Nov. where I am. The rest of the trip went fine and when I got back I read here and checked my Haynes, the Haynes is use less IMO. So what do I order ? And does this sound like that was the problem or is something else a miss? My truck is a three button and I guess has a 233 transfer case. Any help would really be appreciated as all I know about 4wd is the workings of my 67 Dodge M37 which is all mechanical with lock out hubs.
Have you checked fuses and wiring to it?
What are the shift button ligts doing when you turn key on and then press 4W?
Ground pin 13 on the diagnostic connector and read codes from push button lights.
post back code no.