Looking at a new (old stock) Downey header (17410-81) for my 84 toy motorhome 22r-2wd). The application chart shows that its for a 4wd truck. They made a 2wd version (17412-81), but I can't find photos of the 2wd version, so I'm not sure what the difference is. The whole exhaust will be replaced so I'm not too concerned about it 'fitting up' to the existing exhaust. My only concern is clearance by the frame and firewall... I can work it out beyond that. Does anyone know the difference between the 2wd and 4wd version? If not, could you tell me what clearance issues I may find? It won't be returnable, but I don't mind a little fabricating.Thanks much,Dank

 

If its for a 4wd, I would imagine the runners would be longer, allowing the header collector to be closer to the ground essentially. With a solid axle 4wd, there is no cross member, which I believe there is on a 2wd. So the 4wd header may not clear. This is not an educated guess, only going off memory. Which has been known to fail a bit...

If all else fails, if you know someone with a 4wd solid axle 84-85, you may be able to check theirs out and see any differences between your 2wd and their 4wd. Sorry I'm not able to help definitively.

The reason, generally, for longer header tubes is to increase low end torque, which is helpful on a 4wd.

 

On my 85 22re motorhome 2wd, I put a header from LC Engineering. There were two for my type of truck. I got the wrong one first didn't really fit but I could bolt it on. After a year or so I returned it for the right one and this one fit great, less restocking fee. If you can take a chance it wont fit and lose the $$, if it's a small price go ahead. The problem I have is with the fools I had put my exhaust on for me. The flange from the header to the Cat never lines up and blows the gasket right out.