THIS IS ABOVE IS A D10
This D10 above is a modified cab, they extend the cab over the bed, the D10 not was made with crewcab, only D20
The crew cabs, that have no separation from the cab for the bed, are modifications, not from factory
The real crew cabs, original from factory, is like this first one, and the black one is modification
THIS IS A D20, downstairs, now this ugly, bad maintained
Hello, My name is Jonathas Willian, and I live on brasil, or like you call, brazil (its a shit same way, government sucks),
I read the topic, and, I can give information about some pickups like the D20, D10, Silverado..
Best saying, the SERIE 10 was made until 1985, when the SERIE 20 arrived to substitute the SERIE 10, same chassis, new desing, and another improvements, the name was give by the combustivel, like another guy already said,
SERIE 20 diesel = D20, SERIE 20 ALCOHOL = A20, SERIE 20 gasoline = C20, same to SERIE 10, no one call like that here, but if you see one C20 , it is gasoline..
The D20 (serie 10 too), was one truck for the WORK, hard work, and was pretty confortable, and become one vehicle to people that wanted luxe, but in the majority, 90% of D20 you see here, will be with paint scratched, bed of wood (is better for work, but makes the pickup ugly), will not appears a nice and beautiful pickup...
The D20 (will call like that because is better and 80% of the series 20 was diesel

, better for work, better engine, etc ), was made from 1985 until 1996 and the stock sold until 97, when the silverado arrived, with the same chassis of the D20, the S4 for the more simple, and the MWM 6 cilinders turbo diesel for the deluxe edition..
But the better pickup was the D20, in 85, starting the prodution, was sold with the perkins q20b, the same of D10, but with improvements, with 90 horsepower, and torque of 28,1 kgfm (the D10 model was 82 horsepower and 27 torque) those 2 dont have turbo, in 1988 until 1989 was made the 4x4 version, same engine, same suspension but the project used some part of shit (if i know right, was the cruze, that was fragile for the power of the engine, and they stop making it (was something simple, like the cruzeta (dont know the name in english), that broken and dont give the power to wheels), in 1992 was launched the MAXION S4T (T from turbo), the first D20 Turbo from factory, 120 horsepower (2800 RPM), and 38,2 kgfm (1600 RPM), in 1993, one modification on chassis, new brakes, new transmission, new painel, new front desing, some improvements, and in 1995 the S4T was modified to be exported for europe, being compatible with the EURO I, now with 150 horsepower (2800 RPM) and 46,5 kgfm (1400 RPM), the one of the best engines i see.. ultradurable, economic, 14 km/l on road, and 10 km/l on the city, the pickup D20 weight 2,3 tons (simple cab)..
This is my Dad's one, 1994, S4T from factory (this is the custom, don't have AC, but the DH was from factory for all D20)


used for 19 years of intense work, don't look beautiful like before

this was when i was children
This one, are ORIGINAL CREW cabs, 4 doors, the bed are separated from the cab, to being more comfortable, the loads don't make vibrations on cab


Look the separation over here
This is from the selling material:
Cabine Simples (simple cab), deluxe, and you can see on the image, another type of the simple cab, the simple cab with extended bed

Cabine Dupla (dual cab, or like you call, crew cab)
This is the engines information, for who is interested
S4T
S4T PLUS
The D20 Turbo Plus (low speed diesel, max rpm of 2800) was the more powerful pickup, until the MWM 6 cilindros, but the Maxion S4 is better for work, MWM is better to running (high speed diesel)..
Sorry for my bad english, I hope you enjoyed it: D