T60 (1953-D6U) Battery option part number?

[AuroraGuy]

I just picked this unit up...and I was wondering about the "ultrabay" battery....

I seem to get conflicting part numbers....could it be 40Y6789??

does anyone have a valid part number for this battery?
I want to keep the standard battery (6cell) but add a 2nd battery in place of the CDROM I dont use.

I did this on my R40 Centrino and had about 7.5hrs run time

Thanks for any pointers.

-JD

[stephenaron]

I bought the ultrabay battery and have been using it for 2 weeks in my t60p. Great addition. The part number on it is...FRU P/N 40Y6790
ASM P/N 40Y6787