440x2 and HPX2 differences

[Phillipv74]

what are the differences between the Tyco 440x2 and the latter Tyco Mattel HPX2?

[Phillipv74]

are the parts interchangeable between the 440x2 and hpx2? they look almost alike. I have experience with the 440x2, but got out of slot cars around 1995. so I know very little about the latter Tyco Mattel cars.

[AptosC6]

are the parts interchangeable between the 440x2 and hpx2? they look almost alike. I have experience with the 440x2, but got out of slot cars around 1995. so I know very little about the latter Tyco Mattel cars.

Sorry that no one has responded to your question.
The two wide chassis types are very similar. Main differences are the actual chassis (though they are interchangeable) and a 3 ohm armature in the Mattel version (HPX2). The remaining parts are very much the same. The Tyco chassis is preferred as it is more accurately molded (the holes are located better, etc.). The HPX2 chassis were made in very old and poorly modified molds and are less accurate.
The 3 ohm arms will be faster on tracks with long straights but are usually too fast for most home tracks.
A simple way to get performance out of a HPX2 chassis is to use P4 traction magnets (turns a pigs ear into a silk purse). These can be procured for reasonable money from Harden Creek, Lucky Bobs and many others.