Does the faceplate or writing on the pump say anything about the specs of the existing pump. Things like max pressure, usually in "PSI", and flow, usually in "GPM". Once you have this, then look at an equivalent at your local RV supply location.
2002 35R Southwind, W22 8.1L Vortec UltraPower, 19.5' wheels
Toad: Wrangler, lifted and on 35" tires