Engine Revs seem high, could the tachometer be wrong

[Snowey]

Hi
Had to remove the cluster on the 320 to put some new gears on the speedo and notice the date on the cluster is 27/03/92 so not a 1988 original cluster. Got me thinking that maybe it is from a 318i and this is why the rev counter seems to read high (3200rpm at 50mph and ticks over ar 1100rpm). The code plug has BMW18 1385364 which according to a 2017 post is for a 318i. Can someone just confirm this and the Speedo rpm readings fr me before I start to try and sort this out.

Thanks David

[Speedtouch]

Correct, according to RealOEM, it's intended for the 316i/318i with either M40 or M10 engines.