Help with Tach on Detroit Diesel 6v53

[Jerryhope]

Hello,
I am new & I hope someone can help me.-- I just purchased a 1969 American LaFrance Fire Engine. I am told it has a Detroit 6V53N engine & Allison tranny..
The dash tach does not work, the pump panel tach seems OK.. Hard to see it whilst driving .. The Leece Neville alternator has 12v & ground terminals, also has 3 other terminals which Leece Neveille tells me are AC taps, used for tach and also for a step up transformer to supply 115v ac POWER.
It appears the tach on the pump panel is hooked to one of these terminals..
I cannot find a dash mount tach to use on this truck without a hassle such as drilling the balancer or strapping on the alternator..
Is there a decent tach available that will hook to the alternator as original ?? I am replacing all dash gauges, likely with the Old Tyme series from autometer..

Thanks
Jerry
jerryhope@compuserve.com

[LMJD]

It's been mucho years (thankfully) since I worked on any 53 series, but I'm thinking originally a mechanical tach drive ran off one of the accessory drive gear covers on the back of the engine. GoneFishen, a Detroit mechanic here, still works at a Detroit shop, hopefully he'll have better information.