You won't fry anything. They both have the same pins with the same
functions. I have seen pairs of both types used in that relay box.

The 53 is an improved version but not much different. It has a small
resistor inside across the coil to suppress electronic noise the relay
makes.

Mark

Clint Kolda wrote:

> I went to the local VW dealer and picked up a pair of fuel pump relays.  The parts they gave me are labeled #53 and the part number is 141 951 253B.  When I got home I opened the black box above the coil and I see a pair of #24 part number 171 937 503.  Am I looking at the correct relays?  Is the #53 a newer replacement for them?  They appear to both be 40 amp relays, but I don't want to fry something by swapping them.
>
>   Thanks,
>   Clint
>