can I weld aluminium this thick with a 170 amp mig welder?

[Richard.]

does your machine have a 4 roll drive system.
This makes all the difference with Alu.
Even with your list of Alu parts as you mentioned above it can be a nightmare with a 2 roll.

 

[arther dailey]

duty cycle, ye thats a special thing that lets all the smoke thats trapped in your machine come out all in one go.

 

[Liquid Metal]

One point, and dont mean this disrespectfully, but....
If your unsure about it, being as its for a roadgoing vehicle and not just a little patch in something thats started to corrode then you really shouldnt be welding it.