Hi,
Do not want to spoil the deal to anyone but these pressure gauges are not the e30 M3 but the e30 320is!
Model that came with the famous block s14b20 and 192cv, close box as the e30 M3 and was only sold in Italy and Portugal!
This in Portuguese but you can already get an idea of the car!!
http://forum.motorclassico.pt/showthread.php?t=7705
Good luck with the sale .....