sentences:  The exception is some M109A3 shop vans.A small number of M109A3s were upgraded to A4 specifications using the M35A3 upgrade parts and procedures.As-built original Pre A2's are gasoline-powered, A1's use the LDS 427-2 multifuel engine, A2’s use the LD/LDT 465-1c multifuel engine, and A3’s use the Caterpillar diesel.