Are there any marking on the turbo housing to indicate what size it is? With out taking it apart. I’m trying to figure out what size mine is I know if its stock it’s a 21cm housing. Is a number cast on it that says “21” in the same place as where the 16 cm housing has it cast? It does not look very large. Pictures?? Truck 91 intercooled

 

Welcome to DTR. The number is on the backside of the housing, you'll need a mirror and a flashlight. You should have an 18.5 cm.

 

In '91 on the aftercooled trucks the stock exhaust housing was a 21, so Blueturbo would have a 21 housing stock. The numbers are on the housing, it is just hard to see. If you have a 16 housing, though, for comparison, you can see that the 21 is physically bigger.

 

Housing was a 21cm I changed it out this weekend for a 16cm. I got a good deal by digging, ($75). What is interesting is how much quieter it made the truck. (Open exhaust no muffler) than with the 21cm.

 

Well, more exhaust energy is getting turned into manifold pressure -- a good thing all around.

I bet the turbo whine is louder, though. ;D