Perkins M30 Alternator Tacho

[Cosso1]

Since having our river cruiser the tacho has never showed revs while running, needle is always at zero. The hours counter works and back light, so I know there's power to it. I'm of the understanding that the tacho is ran by the alternator. The alternator is a 40amp Cargo/Holger 113562, does this have the output connection to tacho? I am looking to upgrade to the 90amp Prestolite 66021590m which I know does have the tacho connection.
I'm just curious as to whether the original alternator does control tacho or is there another method with this engine?
TIA

[GordMay]

HC-CARGO* Alternators & Starters
➥ https://hc-cargo.de/Files/Filer/HCCa..._2015-2016.pdf

Wiring diagram for Perkins Perama M30 marine diesel engine
➥ https://www.scribd.com/document/6588...ctrical-wiring

* The Bosch Company acquired Holger Christiansen A/S, in 2008. HC-CARGO has been a Bosch Group brand, since then.

[Cosso1]

Originally Posted by GordMay

HC-CARGO* Alternators & Starters
➥ https://hc-cargo.de/Files/Filer/HCCa..._2015-2016.pdf

Wiring diagram for Perkins Perama M30 marine diesel engine
➥ https://www.scribd.com/document/6588...ctrical-wiring

* The Bosch Company acquired Holger Christiansen A/S, in 2008. HC-CARGO has been a Bosch Group brand, since then.

I can't seem to see the Perkins wiring as it's wanting me to subscribe to some sort of service. I have managed to find the alternator that is on my boat at present. It has a B+ and R L connections, so assuming no tachno connection.