Where is the EGR located on a '91 B2600?

I just had the check engine light come on my 91 B2600. The truck is running great and very smooth. It has 224,000 miles on it. I recently put a bottle of Sea Foam into the gas, oil and pcv valve. The light came on shortly after. I have located the O2 sensor but can not find the EGR valve. Any thing else I should check?

No EGR,it is fuel injected.EGRs are on the 2000/2200 carbed trucks.