polarity switching spdt relay

I have been out of the electronics scene for a while.  Where can a SPDT polarity switching relay be purchased ( I searched the forum and see pin-out diagrams but no manufacturer or model number.) ?

I put two Hummer H3 mirrors (three wire polarity reversing system) on a Toyota FJ Cruiser (four wire system - up, down, left, right).  I need two acquire two relays as shown in the following schematic I saw in this forum.

DK in Santa Fe

Any relay can reverse polarity. Either read the relay section or follow this:- The coil is noted as 86 and 87 If you make 86 a constant POS, and switch 85 to ground (NEG), you can have another POS input at 30 and output at 87 (ignore 87a). Thus you are changing the NEG at 85 to a POS at 87. Vice versa, constant ground (NEG) to 85, switched POS to 86 ground to 30 and output from 87. Thus time you're switching POS at 86 to NEG at 87. Any 4 or 5 pole (ignore 87a) Bosch/Tycho cube type relay available from any auto parts store.

By the way that diagram has nothing to do with what you're asking that's for open circuit rather than grounded at rest. Look up 5 wire relay interrupt.

It sounds a bit like my electric windows. Currently (pun intended) using a center-off DPDT switch but will replace with center-off SPDT switch controlling 2 separate SPDT relays for the window up & down. (Reason for relays is less heavy inter-wiring for master and other controls and overrides, alarm or exit control, inclusion of soft-start, etc.) As to SPDT or DPDT relays, there are lots on the web.