Spacelab (conversion model 443)

Spacelab (Model 443) is an electro-mechanical, single-player Add-A-Ball pinball machine from Williams Electronics, dated June 14, 1974. It is not a distinct original design but a conversion of Williams' 'Skylab' game: Williams took replay-version Skylab units off the production line and converted them to Add-A-Ball-only play by removing the replay number wheel and replacing the backglass with Spacelab branding. Everything else, including the playfield and its 'SKY LAB' identification, carries over from the original Skylab game.

Gameplay includes two flippers, two pop bumpers, two slingshots, an end-of-ball bonus, and a looping captive-ball feature using five captive balls, which scores a Special when all five are on the lit side. Sound comes from three chimes and a knocker.

This Model 443 should not be confused with the separate, limited-run Model 444 'Spacelab,' which preceded it and used a different design. Model 443 can be identified by details such as a backbox insert with a large hole for the unused replay unit and a backglass silkscreened for a maximum of 199,990 points. Serial numbers fall within the same range as Skylab units, and it isn't known how many games were converted or whether they are included in Skylab's official 3,651-unit production count.