No..He did not play Slingerland on Zeppelin I..There is a pic of him from the book,A Thunder of Drums-- John Bonham- The Godfather of rock drumming, where he is clearly playing the already endorsed Maple kit in the studio sessions for that album.. I have the book and it states all the kits he had,including the Slingerland from the early club days.
That pic is from the Led Zeppelin II recording in 1969. As far as I know, he wasn't endorsing any maker at the time of the recording of Led Zeppelin I in October 1968.
Carmen Appice is quoted on pg 94 of 'Thunder of Drums' that "Bonham was still using his little Ludwig kit, the one he used on the first album". Apparently that was in Feb '69, before his double bass maple kit had arrived from Ludwig.
Following his endorsement of Ludwig, the maple kit was used on Led Zeppelin II.
The green sparkle kit was used on Led Zeppelin III, IV, Houses of the Holy, and Physical Graffiti.
The only kits I've read that he owned prior to endorsing Ludwig were a red sparkle Trixon gifted to him by his parents and a green sparkle Ludwig Super Classic used in Way of Life in '66-'67, and with vocalist Tim Rose in '68.
