I started researching axles, chassis, and engine options. I settled on the GMC W4500/Isuzu NPR for several reasons. The frame width was the same as the original, front axle is only 1" wider than the original, wheel bolt pattern is the same as the original 57 (its 6 on 222.25 mm but works out the same as the 6 on 8.75) and they are every where. I looked at all the medium duty chassis but the axles were too wide. I found a 2003 GMC W4500 HD with 73,000 miles on it. It had a 350 vortech with a 4L80E tranny. So I bought it.
