Do I have an M600 or M400 Chasis?

[mr27t]

 I just bought a 1978 32 foot Executive Motorhome and the VIN # shows that it is on a Dodge M600 chassis. I found a website that say's to check the wheel lugs, if it has 8 lugs it is a M600 chassis, if it has 6 lugs it is a M400 chassis, and if it has 5 lugs it is a M500 chassis.
I have 6 lugs and by the information I have found, it would be an M400 chassis.
The VIN# indicates that my RV is an M600, the lugs information tell me otherwise.
How can I tell for sure what I have exactly? Is it an M600 or an M400?

I am completely lost with this beast, HELP!!!

[Elandan2]

You definitely have an M600.  The wheels on an M600 are 6 stud, M500 are 5 stud and M300 and M400 are 8 stud.  Get yourself a Dodge Motorhome Chassis Service manual.  The best resource for information.  (I got this info from page 22-9) of the 1976 manual).  In fact, pdf copies are available right here!!  Rick

[DaveVA78Chieftain]

Also for that year
M300/M400 = 17.5" tires
M500/M600 - 19.5" tires

[vincewarde]

Definitely M600.  I have one.  Taking about wheels and lugs, be advised that the lugs on the drivers side are reverse threaded.

[GTA351C]

Interesting thread, I am trying to make a '35 Ford 1-1/2 ton into a driver at least and found out that the M500's are the ones that have 5 lugs with the 8" BC, same as my truck. I just got the spare of a rig at the local wrecker and it says 17" rather than the aforementioned  17.5"  Just got one for a trial fit guess its a widowmaker, were the 17.5's and 19.5 both solid rims?

Thx!

Bob

[Oz]

19.5 solid. 17.5, depends on what year.  Pre-74 were split.  74 and later,  one piece  (Budd rim).