bought t40/r50 ultrabay batteries, fit t420s?

[kaitanium]

in theory these would fit right?
when i got them in, all the shapes look right except when i tried to put them in they were slightly snug and didnt drop in smoothly like the optical drive does (you can make out the streak marks from rubbing within the comp). they do go all the way in except when they hit a tab (pointed out by the pic). im not sure how the current ultrabay battery 43 behaves so i have no idea how ultrabay batts are supposed to fit.

now my questions are:
1. i assume it is safe to shave off that tab?
2. and if i do so, the battery will work inside the laptop as all connectors are the same? looks like the connector is the same if i peek into the ultrabay

[twistero]

I believe they will not fit. ThinkPad batteries changed before the 60 generation, so batteries for T43/R52 or earlier does not work in later machines, and batteries for T/R/X60 or later does not work in earlier machines.

[kaitanium]

well according to this post of mine which i asked backwards, not sure why i did that. if the new one is compatible with the old then that means the old should fit the new, thats if the connectors are the same. http://forums.lenovo.com/t5/T61-and-pri ... d-p/880933 (i posted a same thread here on TF too)

the X series batteries for sure as they dont have an ultrabay built in.

i wonder what model is the battery i bought, an ultrabay battery 42?

maybe i have a hole in my logic right now.

ill ask the same question on lenovo too just to see the response
http://forums.lenovo.com/t5/T400-T500-a ... d-p/891431