what do the markings say

thats a hell of an idea. cant believe i didnt think of that, thanks for the info on the 4 ...

Actually the yellow circle with a four is the bridge number. It has to do with the gross vehicle weight of the vehicle.

It has to do with the goss weight, correct, but it has no direct correlation to GVWR. Some people erroneously think that since these trucks "Gross-out" near 8,000 lbs (4 tons), that the bridge plate numeral indicates the actual "4-ton" rating. It does not. This is just a conincidence with our trucks. It is a classification, not a true value.

With a trailer, the M715 bridge rating is a 6....just as an fyi...it would then be close actually to the 6 tons that rating would imply if you read it that way...but it would be erroneous to do so...if you had a 5 or 10 ton 6X6, the numbers wouldnt be close at all.
brute4c

And along with the "6", you are also to change the top plate to "C" to indicate the weight calss refers to the Combination vehicle (prime mover and trailer).

Good catch Mr. Bumpy....what ever happened to your cartoon show??
brute4c

Bastiges cancelled me.

my truck dosent have a plate on the grill, should it or did it at one time?

It may never have had one...hard to say...you see them on ebay from time to time...bridge placard or something close to that...just do a M715 search and see...
brute4c

i was on ebay the other day and saw some for sale but didnt know what my truck would of had.. i dont think it ever had them now that you say some did and some didn't, it still has all the other original marking so if it ever had the plates it would most likely still have them.