parts and value question

[too much stuff]

I have a c-30 dually with an odd rear end. The truck is factory built, option in glove box reads "D R wheel conversion" The center section bolts into the front, and appears that axle tube is longer on pass side. Front side looks similar to a ford 9" (but bigger) Also says no slip rear end. Looks narrow also. What is it, and what is it worth? Also wondering about value on 72 blazer rear seat. One small tear, otherwise nice, with seat belts attached. Does anyone have pictures of factory bumper gaurds? Sorry no pictures, and stuff not for sale. Thanks for any help and opinions. too much stuff