Was out on the spark today when the rebound disappeared on the nude shock and it started making all sorts of “im f@@ked”noises.Now the question is do I get it serviced and returned to its usual averageness or do I change it for a rp23.If this be the case then what size shock will I need?

Not much to go on here as the Spark has run a nude since 2007(?)
Current generation Spark runs a 190×50 (7.5×2) shock.

The current Fox nude is a wildly different shock to the current frames initial DT nude.

I think older generation frames were 165×38 (6.5×1.5) or something much shorted than currently, but yep, RP23s/Floats are available in that length

Incredibly disappointing failure to deliver on promising thread title…

Its a 2011 and I think you’re right about the 165×38
cheers

I’ve got a 2012 Scott spark and the nest thing I ever did was replace the dt swiss rear shock. Got me a nice rockshox monarch rt3 on a special deal and it feels like a completely different bike. If you can stretch to a new shock I would highly recommend it!