Relay with different mounting bracket, same number, used on later 140, 164 for OD, also for reverse light relay. Useful post here. Late bracket probably less prone to letting water in via the mount rivets.
https://www.brickboard.com/RWD/volvo...sch_sr803.html
Julian, are you coming to the Bentley meeting? If so I will bring a relay for you to try. Note: J type OD didn't use a relay. Don't know which type you have.