On my Mog's 617Turbo there is another spot above where the banjo bolt for the line to the Alda is mounted to the intake manifold. I'm pretty sure I saw the same hole in my 300D. The hole has a threaded plug in it. I beleave this hole is same thread as the banjo bolt below it. If so then another banjo bolt off of a junk 617 can be mounted there and your boost gauge hooked to this. A much more accurate arrangement with this direct connection.

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"If anyone knows other lessons I need to learn, please tell me. I'm tired of learning them the hard way".
by JerryBro

The Glow Plug Wait: This waiting period is a moment of silence to pay honor to Rudolph Diesel. The longer you own your diesel the more honor you will give him". by SD Blue

My normal daily life; either SNAFUed- Situation Normal... All Fouled Up, or FUBARed- Fouled Up Beyond All Repair

62 UNIMOG Camper w/617 Turbo, 85 300SD daily driver- both powered by blended UCO fuels