Save yourself the trouble...the older packs have
tabs that are already welded to the battery....
leave them..just cut the tabs halfway, when you have them in their new position solder short
little pieces of bare 12 guage copper wire to
bridgefrom the cut end of one tab to the other
use good grade of electrical solder and PASTE FLUX the secret to quick and easy soldering for
me it was anyway.
Eager to help any questions about it ask away
I'll try to help....