seat track cleaning/restoration

My front seat tracks (1970) are not designed to be easily disassembled. They are full of dirt and old grease. The local machine shop has a "tank" that they use to remove grease from parts. Are there any plastic parts inside of the tracks? From what I can see, they are all metal and it should be safe to use the tank.

Assuming I can get these cleaned up, is white lithium grease good to use for lubrication on these?

Thx.
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Author: Jeff