75 GMC Full time Vs. Conventional transfer cases

[Jimmy Canuck]

I have a 75 GMC half-ton 4x4 with conventional hubs but it has a 350 in it. Is this stock? I read some old advertisements and it seemed to indicate that only conventional 4x4 hubs came with 6 cyl. engines or was this only on Chevy trucks? I can't check the vin on the cab as the prev owner threw out the original vin tag when switching cabs.....

2nd. What is the difference between a conventional 203/205? transfer case and a full time one?

3rd. My cousin told me to watch out for trucks of these years 73-77? because sometimes former owners have changed the hubs from Full time to Conventional and it does something to trash the transfer case. Maybe lack of lubricant or forgetting to lube the case??????

All this is because when the truck is running either the transfer case or a throw out bearing in the clutch is making a hell of a racket.