Hi Luke, no doubt you are correct that in the Aus market, the PE175 C and Ns had A steel base, but I think we need to be careful before suggesting that this is THE, if that means, 'the only' steel base. The only bike to my knowledge that was sold in all markets with the alloy tank was the PE250B. This bike had a one year only steel base (whether this is also the same as the RM250A base is another question). Frosty is correct about the use of alloy tanks on later bikes in the UK. Much later bikes I think in Belgium also used them. These bikes obviously have a seat specific to them. All I am saying is that its wise to exercise a little caution when trying to find an alloy tank and seat combo, especially if these parts are missing from your bike and you have nothing to work from, hence my suggestion that if anyone is thinking about doing this they find a tank and 'appropriate' seat. I have acquired an unfortunately large collection of PE (and RM) B/C/N seats (metal and plastic), not least through trying to solve this particular puzzle myself (some with the 'help' of forum info), and only ONE of those works with ONE of my alloy tanks, suggesting that there might also be tank mounting point variations too, on both (US/UK) tanks and frames. All of my experience relates to 250s though tanks and seats are from 175s and 250s.
