I have a 92 D250 Auto 518 with OD Can a dealer tell me from my Vin I have the window sticker but it dont say/ I do have the Anti spin diff.

3.07 or 3.54

 

I believe it should say on the inside of your hood. When you open the hood look up and to the right.

EDIT: I may have just stuck my foot in my mouth. I believe you might have meant there was no tag stating what gears you have when you said that you have no tag.
Sorry!

 

lets see if i remember the right procedeure. jack the rear axel off the ground, chock the front wheels and use jack stands. throw truck in neutral. crawl under truck and mark a line on driveshaft.rotate rear wheel exactly one turn while watching how many turns driveshaft moves. 3 turns = 3.00s 3.5turns = 3.50s and so on. im sure if i have this wrong somebody on this site can set me straight.

 

Your the man...I could not find the tag on the rear, but as you said it was under the hood I have 3.5

 

Hahaha, cool! Glad you found it!