Ok so I'm not going to suggest buying a used phantom impact that doesn't exist in your area, like some people do. Not sure how that helps anyone.
What I will do is say I've used the 1/2" version of that gun (The "Earthquake" series) and it beat out an IR 2135timax by an order of magnitude and was neck and neck with the Aircat 1100 in a home garage.
I personally would suggest getting the 1/2" version, especially working on the suspension, in the future if you find it cumbersome get the 3/8" but the 1/2" is more than any home garage could ever use IMO.
With your 20% off it's around $75. Don't forget your coupon.
The Earthquake series from HF has always gotten good reviews and this new line is better than the old version (owned one of those as well). It's one of the few things at HF that isn't junk. I recently did my front suspension and then after that swapped transmissions on my car, using that impact, it handled every bolt with ease including control arm bolts, sub frame bolts, etc. It also will take crank pulley bolts and axle nuts off with enough air, 90+ psi at the gun which means a tank pressure of over 120 psi.