i'm talking cab and chassis. i'm looking at a srw cab chassis f350. is it just as strong as f450 f550 frame. reasons being i was thinking of putting f450 dually rear and front on it. making it into rollback

 

No. The F250-F350 given a same configuration are the same frame unless the 350 is a chassis cab. The F350 chassis cab up to the F550 chassis cab had straight frame rails from the cab rear. The rails are flat in other words and don't flare up behind the cab like the pickups. The F450 F550 frames are a good bit thicker than the 250 and 350 frames. I don't have measurement on thickness differences right now though.

 

yes it is a chassis cab f350 single wheel chassis cab. So the frame is weaker than f450 f550 chassis cab frame???

 

I wouldn't necessarily say weaker as it is not weak by any means, but unless they changed something, the F450+ frames were thicker than the F350 chassis cab ones.

 

for that f350 is the frame the same width as the pick ups? would the rear end fit in f250 f350 srw pickup frame?

 

The rear end of an F450 or F550 may fit, although you will have to do the spring perches differently and have different leaf springs. The larger rear ends used skinnier leafs in their setups.

 

We have a 03 F-550 dump truck,even with a subframe all the weight goes on the tailsection when you raise the body. The frame can develop cracks above rear axle because the bottom edge of frame is notched for the inside shocks too clear and frame is thinner height wise in this area. Double frame,plating,fish plating of frame in this area is a good idea. Truck doesn't seem to flex as bad either. Rolloff or roll back could put weight on end of frame. plowking

 

I own F450 and it is darn heavy. The truck wit dump bed, liftgate and full tank tips 10,000 lb.
I beg you to reconsider the F450 rear differential. My truck runs about 2500 rpm at 65mph giving me lousy fuel mileage. Than I am taking 6% grades having 10,000 lb payload without downshifting from 6th gear. I researched differentials and seems that the high ratio differential is the only option for F450.
Meaning if you use the F450 axle you are going to have the same dilemma I do.

 

i got a nicr rollback but its on an old cab over isuzu. the bed can hold 10k so i didnt want to put a f350 under it unless it had the double frame.

it's a 2000 srw cab chassis f350 2wd, i was thinking maybe all superduties had the double frame.

supposedly the thing runs good and it has the zf6. it would be sweet if i can find a long rack body truck with a blow tranny or engine. sometimes the gasser automatics rack body/ stake bodies. go cheap. really want a f550 but i can always up grade the rear end later because the frames are the same. would be even sweeter to find a rack body with ext cab. that would be a sweet rollback

What is fish plating??

 

on the old body style the f350 had a weaker frame than the f450 superduty. I'm wondering with the new style trucks (99+) i'm thinking the frames might be the same

f250-f550. i have an obs f450 superduty and my 2000 f250 cab chassis srw the frame steel is the same thickness???

 

A while back, I know that the Dana S135 was gearable down to 3.73 if desired through the supplier. Since the reduced width S135 Ford used no longer is made, I am actually not sure if they can still get the parts for that...

 

katjek1 what gearing is in your f450?? i have an obs f450 and it has 5.30 in it.

 

i playing with my project and the 06 f550 frame has a different steering gear and the bolts and holes are way bigger than f250 or f350. the steering box is the same 99 up i bought one for nothing.