Isuzu 4 cyl would be your best bet. You should be able to find one that bolts up to the GM transmission. They were offered in the S10 from the factory. My second choice would be the VW as there are more adapters available than the Mercedes.
1993 K3500 - Peninsular 18:1 engine, marine injectors, high capacity cooling, AL Core Radiator, 3" DP and 4" exhaust, ISSPRO Gauges, Girdle, AMSOIL Dual Oil Filter System, 1997 Air Filter(trashed the K&N), 395K on Body, 165k on engine.
1997 GMC Savana - 6.5 TD
1966 CJ5 - V6 Gas - highly modified
1967 Jeepster - Stock
1986 Jeep CJ7 - Stock
1993 Grand Cherokee - 6.2 diesel
2007 Grand Cherokee - 3.0 diesel