1981 Strat = 70's Strat?

[Telarkaster]

The other guitarist in my band picked up a two tone sunburst, black pickguard rosewood necked hardtail Strat on Ebay this week.

It was advertised as a 1981, but he took it apart and dated the body and pots as 1979, and the S9xxx serial number on the neck is from 1981.

He already has a 1976 hardtail Strat and this 1981 model is identical (other than colour) to it except for one thing: the 1981 weighs a ton!

Were they making 1981 Strats with 1970s parts that were lying around at the time?
If so, then he scored a bargain because he paid half of what a 70s Strat is going for now, for basically the same guitar, just because it's dated as a 1981 on half of its components.

By the way, I played it last night and it's a beaut. I was in guitar heaven, really enjoyed it. The only thing is that it doesn't have the quack that my 2005 Am Ser has, maybe because of the weight or the fact that it's a hard tail...

Sorry, no pictures, not my guitar...