how do you tell 460 Ford engine from 390 with out tearing down?
I have 2 1973 Ford F250 trucks and was told one is 390 and other is 460. All info i found was on vin id and i do not know if engines have been changed or not.
ford truck

The 1999 Silverado 1500 is an important vehicle to Chevrolet for the extended cab pickup market segment. The Base is a member of a series of three trim levels for the Silverado 1500 which include Base, LS, and LT. The two-door truck with its four-wheel drive is positioned to aggressively fill this niche for Chevrolet. There is strong competition from vehicles from Lexus.

The restyled Silverado 1500 WT is equipped with a General Motors 4.8-liter 8-cylinder engine that utilizes a total of 16 valves. The Vortec engine is paired with a General Motors 4-speed transmission. This configuration has proven to be a successful design for Chevrolet.

The Silverado 1500 LS is equipped with a General Motors 4.3 liter six-cylinder engine that utilizes 12 valves. The Vortec engine is mated to a New Venture 5-speed Transmission. This configuration has proven to be a successful design for Chevrolet.