I used to have a 79 that used a non lambda engine. The 76 also is a non lambda
system motor. The hose going to the exhaust manifold if it is like my old 79
is the pipe for the egr system. You should be able to run the motor just fine
without the egr functional. The other possible use is the pulse air system
that volvo used for emission control. I don't know much about the pulse air system. Your probably fine without either system.

Dave 82 242ti 278k mi.