I switched my wipers to 12v electric 2 yrs ago & still have the 2 stage fuel pump. I would like to change it to a single stage one but am a little confused. I saw some on ebay listed for a 54 or 55 truck. Didn't they have vacuum wipers too?  There are also some listed for 272,292,312's from different years.  What about the rod length on them? My engine is a 55 272.    Any info would be appreciated! Thanks, Mike