CM hauler bed, model TM

I've built 3 5er friendly beds for my own trucks. I like doing my own so I can cut off the excess useless frame rails at the back end of the truck and build a bed that's shorter behind the axle for more front storage door access on the 5ers. On the last one I used 11 ga rectangular pipe (various sizes, bigger for the deck and smaller for the sides and headache rack) and it's 3" above the truck frame + 1/8" treadplate. The sides taper down towards the back end for plenty of clearance for the 5er and I welded in members for the 5er hitch mounting and g-neck ball and built an integral bumper. The deck plate is 1/8" 6061 t6 and the sides, front and rear are 1/8" polished aluminum. Even with all that aluminum that sucker still weighs 850! $2000 in material including the lights and 3 months of work - nights and weekends. $8000 installed for the CM w/hitch sounds very reasonable! Craig

Alannyiri wrote:
I've "solved" this dilemma by going for a Knapheide Westerner body instead. The bed height increase is lower - 5.5" rather than 7.75" for the TM - and the toolboxes are all just 12" above the bed. There is not a taller box in front, so that concern is eliminated. Not the maximum amount of additional storage (about 40 cubic ft),but the maximum amount of confidence. Thanks again to you who responded!

Good decision, it weighs about 1100 lbs plus weight of the bumper. Probably about 800 lbs more than the stock bed/bumper.

I've "solved" this dilemma by going for a Knapheide Westerner body instead. The bed height increase is lower - 5.5" rather than 7.75" for the TM - and the toolboxes are all just 12" above the bed. There is not a taller box in front, so that concern is eliminated. Not the maximum amount of additional storage (about 40 cubic ft),but the maximum amount of confidence. Thanks again to you who responded!

avvidclif1 wrote:
Excellent response Larry and well thought out. The difference you left out is the weight of the 2 bodies. The difference between the aluminum body and the other comes straight off of your payload capacity. If all the numbers add up for reduced payload I can see no reason for the lighter body.

Funny a quick search didn't show any weights published for either.

Good point, steel hauler beds are heavy, they are overbuilt for dedicated tow vehicles. With the 4" frame rails and 3" cross members they use a lot of steel. Then add in the storage boxes and sides. The TM body probably weighs 2000 lbs. Utility beds, while not as fancy as a hauler bed are somewhat lighter. Mine is about 700 lbs vs. about 300 lbs for a stock pickup bed, so minimal impact on payload. Now 11 years old and on the 2nd tow vehicle.

Thank you gents for your knowledgable input. I'll be visiting my RV dealer this coming week, and will give them this info. Hopefully, we'll come to a decision which will be workable. I'd hate to give up the additional storage that a utility bed like the TM would provide, but I'm also wary of the low clearance issues which the new, taller pickups can introduce. This is exactly why we bought the Fiver first, to allow us to then make the best TV decision. Any other ideas?

Excellent response Larry and well thought out. The difference you left out is the weight of the 2 bodies. The difference between the aluminum body and the other comes straight off of your payload capacity. If all the numbers add up for reduced payload I can see no reason for the lighter body.

Funny a quick search didn't show any weights published for either.

With 4 inch tall frame rails and 3 inch tall crossmembers, the bed floor sits 7 inches above the top of the truck frame rails. Stock pickup beds sit 2-1/2 inches. Utility beds like mine sit 4 inches above the truck frame. That might be the problem, but there are specific low profile hitches designed for flat beds to address this difference. However, with a short bed truck, I wanted a slider hitch and therefore cut and recessed the center of the floor to accommodate a standard hitch.

Second problem is width between the truck bed side rails. Pickup beds are about 64 inches, but utility beds and that TM bed are just 50 inches due to the side storage boxes. This is an issue with fivers that use extended pin boxes because the back of the pin box will hit the side of the truck bed. There are three solutions, 1) use a straight drop pin box or a short extended pin box not to exceed 25 inches. 2) make sure the extended pin box rides over the top of the side storage boxes, my custom utility bed is a reduced height, the depth of the bed is just 12 inches vs. 20 inches for a stock pickup bed and I have 10 inches of clearance between the truck bed and the fiver gooseneck vs. 4-6 inches with most setups. The TM body looks similar with minimal height above the floor. 3) use a Sidewinder, aka Reese Revolution pin box so the fiver pivot point is like a straight drop pin box.

Third problem is the height of the front storage compartment of the TM body. When making sharp turns, the front of the fiver could hit that front area. However, as long as this raised area is no more than 10-11 inches higher than the side storage boxes, this should not be a problem. Normally, the bottom of the fiver body is 12 inches higher than the king pin height, could be less if optional mounting holes are used.

Finally, historical fiver heights for level towing will have the king pin plate at 46-47 inches high and therefore the fiver body at 58-60 inches. With a few key measurements from CM for the TM body and height of the tow vehicle frame rail (2.5-3 inches lower than load height) you can determine if it will work OK. Also, with the king pin weight and the added weight of the hauler body, the truck will probably settle 2-3 inches.

For reference, my GM 3500 has a frame rail height of about 35 inches, my utility bed floor height is about 39 inches, top of the utility bed is right at 51 inches and the extended king pin box swings over the top of the utility bed. If you use a Sidewinder or straight drop pin box and the TM is less than about 57 inches high at the front storage box you should be ok.