Help with Seiko original Speedmaster battery

[BMWCCA1]

I am the original owner of a Seiko Speedmaster watch designed by Guigiaro in the '80s. I haven't worn it in decades and at one point removed the battery to make sure it wouldn't leak. Now I have a selection of o-rings and want to put the watch back in service but can't find what battery it takes. Seiko reissued the watch in the early 2000s in a limited run of 3,000 but with a new movement. It is considered to be the Motorcycle Watch with its LED display tilted for viewing while holding the bars. Why can't all watches be like Timex and engrave the battery model on the backs!

Its model number could be A828-4000 or maybe SBJ003, but it's hard to tell the original model number from the reissue.

Anyone have access to a battery chart by watch brand and model? I called Seiko but they're on holiday already.

Thanks if you can provide any help.

[BMWCCA1]

I think it might be a CR2016, according to an owner's manual for a similar style watch. Thanks