Just bought a 91 White/GMC With a Volvo Motor. Where's a good place to order parts?

I had that same truck with a DD13 motor. Your going to have to call the dealer, VIN & photo, im sure they can help. The dealer, parts sales counter will allow you to up load a picture to them.

 

https://www.heavytruckparts.net/

With your part number, hit up the salvage yards.

 

x2 on the salvage yards. If you're in the midwest, I'd start with Vanderhaag's...

 

Really it is the same motor, like was used in Volvo F12.

TD 122 is the same like TD123, but w/o EDC, just Boch injection pump.

So many parts are available in Europe, many are available from China.

 

Part, u see is the EPG. Exaust pressure governor.

Used to keep engine warm, to reduce noise when jakes are actuated and for minimum engine braking, also to reduce boost pressure too.

U can easily remove this stuff out and drive w\o EPG

 

Hi, I confirm your engine is a TD122 (because i can see the by pass air to air pipe on the picture above) Yes like someone told you the TD 123 (1992-1994) are also equipped with the same device (also same part number), i recommanded you to replace the exhaust brake air cylinder and keep it working it will be better to keep engine temperature at idle speed and better cab heater.
Ben

 

it is especially important for cold states.

also new volvos have EPG too to keep exaust gas hot for aftertreatment

if u operate truck in warm states u can remove this valve