C or J Motor?

[Chappy]

Hi all, please bear with me, totally new to the world of diesel power.

I recently purchased an 87gmc R2500 to use as a work truck and am wondering, how do I know if I have the C or J motor?

Also, what is thE basic differences in them?

Thanks,
Chris Chapman

[HANK1948]

you probaly have a J motor GM usally put them in 3/4 and 1 ton trucks, but the real tell tale sign is when you remove the air cleaner the J motors will not have a EGR valve right over top of the plenum the 1/2 ton C motors have the EGR valves in the plenum

[doncannon]

Chappy,
If you are standing at the back of the driver side fender and look in the windsheild at the vin number on the dash (little metal strip). Count from left to right 8 digits and this should be either a C or J. However if the motor is not original you could look for an EGR valve. I believe the C code has it and the J code does not. Hopefully others will chime in on their opinions.
Good luck,
Don