One item that you should consider is the trans, since different trans were used in both cars. 3.0 Xs came with a GM trans, whereas the V8 X came with a ZF trans. If you search this forum, there are more problems posted on Xs with the ZF trans than Xs with the GM trans. Towing will just add additional strain to the trans. With BMW lifetime ATF used in the trans, renewing the fluid would be a lot cheaper on the GM trans (Dexron III or VI)compare with the ZF trans (ZF Lubeguard).

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2006 Infiniti G35
2001 BMW 3.0I E53 X5 Build date 08/2000 SOLD
Lotus Europa 1970 Destroyed by fire
Lotus Europa 1970 S2 Renault Powered
Lotus Type 52 1970 Twincam Webers Powered
PORSCHE 911 Targa 1982 The Garage Queen
Audi Avant donated to Kars for Kids
BMW 525IT Sold
Audi 4000CS Quattro Sold
Jensen Healey Lotus Powered Sold
Opel 1900 Sold
Triumph Spitfire 1971 Sold
Triumph Spitfire 1968 Sold
Plymouth "Cuda" 340 Six pack SOLD