160a is plenty if you can find one for a reasonable price most of the nbs upgraded ones are 145a but 160's are out there I had one on my 00, otherwise you have to go custom aftermarket, the ppv/ssv 07-14 are 160a, then they bumped them up to 170a on the 15+, my 18 Silverado was 160a with a factory 110 outlet but I put a 230a from a HD 3500 on it. i think all you have to worry about is the pin's on the alternator harness even a bigger case should still fit, pulley size may vary slightly my belt was tight but it went on.