The only studio recording that Lucas Fox did with Motörhead can be found on their album On Parole.
Some more information on Lucas Fox and his musical career can be found at wikipedia. We recommend you check also his discography at discogs.
Lucas Fox and The Sisters Of Mercy - or The Sisterhood, resp.
In 1986, Lucas Fox was involved in the production of The Sisterhood single Giving Ground and the ensuing album Gift,
where he did the vocals on Colours, Finland Red, Egypt White and the lead vocals on Rain From Heaven.
Quote from wikipedia
Eldritch decided to secure the rights to The Sisterhood name as quickly as possible.
He registered a company under the name and prepared a record to be released on his own label.
In only five days Eldritch recorded a song called "Giving Ground" which he co-wrote with Merciful
Release manager Boyd Steemson and co-produced with Lucas Fox. Fox and Eldritch had met in
spring 1985, when Fox was the stand-in drummer for the Australian support band The Scientists
on The Sisters' UK tour.
Eldritch recorded all instruments himself (guitar, bass, synthesizers and drum programming),
while Fox programmed some additional percussion tracks.
At the end of The Sisters' Spring Tour Tune In... Turn On... Burn Out in 1985, Lucas Fox was invited
by Andrew Eldritch to join The Sisters on stage and sing with him Knockin' On Heaven's Door,
see the lovely still video here on the right side (with thanks to the uploaders).
We very much recommend you check this link for a recent interview with Lucas Fox about his entire musical career beginning with Motörhead
over to his involvement with The Sisterhood and how it all came about ... Another extremely interesting and more Sisterhood-focussed interview is available
at the wonderful blog I Was A Teenage Sisters of Mercy Fan under The Sisterhood - interview with Lucas Fox