Between 1979 and 1983, the same mold for the figure was available carded and by mail-away (via proofs-of-purchase or Sears). The spring-loaded rocket pack was never produced beyond some small handful of prototypes, while some foreign versions have removable rocket pieces.
There are some noticeable differences between the figures, such as the embossed copyright mark on the leg either noting Hong Kong (light brown belt and visor), Taiwan (medium blue vs. light blue), or simply no country of origin (COO). But there are also some subtle paint and craftsmanship variations.
For even more in depth analysis of the COO (country of origin) variants, see WBobaFett's analysis on SWSpaceClub.com.
Hasbro (previously Kenner) re-issued this figure in the 2010's with a working rocket-firing backpack.