Heavy

Hello. Mechman offers a 250A alt for the GMT900 Tahoe that appears to be just a drop in/"plug & play" unit. Other than performing the big3/4 which is a given, is there a chance installing the alt on factory wires would cause any issues until newer wiring can be performed? The reason I ask is I found a shop to install the system however they won't touch alternators, which I find a bit odd but I guess it is what it is. Thanks you!