Yes they are vacuum lines. Good call on that!!
Not quite sure how they work.
Hey! I contributed!.
The front axle has dually front hubs. The h1 rims had enough back spacing to allow me to leave the front hubs alone.
I plan to stick with that rim and tire set up for the time being.
Good luck with your axle search
Personally, I like the H1 rims. I know they're heavy but that doesn't bother me. I have a recentered set on a J-truck I'm doing and I like the look, plus the tires for them in the size I want are plentiful and readily available at decent pricing. Problem is I don't think I can run them in a dually config other than the dually front axle. I don't think they'd fly on a dually rear.
Next thought is "ok, change out the axles to SRW config front and rear. Problem with THAT (I think) is running a stock H1 rim is going to offset the rear tire WAY inside from where the factory outside dual sits.
Next next thought is "ok, go ahead and have the rims recentered", but I'm not sure even that is going to put the tire back in it's more or less factory position.
Next next NEXT thought is SRW front axle, dually rear axle, recenter the rims for a 4.5" backspace, and run the dually axle in a SRW config. I "think" this might keep the tire close to it's factory position, given that the tire is going a be a couple three inches wider than the factory.
This has been giving me a literal headache for days. For some reason I just can't quite wrap my head around how to get where I want to be. I want a 36-37" tire. I'd rather run the dually axles. I don't think I can do it in the rear without having to add so much spacer I end up way too wide in the back. I'm willing to run SRW in the back, but dont know for sure how to go about it to get the right track width.
Grrrrr.