I have 74 FSM, can check what it shows tonight. I thought both of those gizmos were 74 only.
They also had some kind of timers for egr? I have the plug on my harness. Got the ' black box' off ebag, but have not tried it. May just put it on for completeness appearance. That was near the AC dryer. Also ive seen some 75s have another magic box was on firewall above the blower.... I should get a 75 manual to figure this stuff out. The 74 book just happened to come my way and was close enough for almost everything. Gotta love all the mystery gadgets they came up with in mid 70s. LOL