The quick answer you need is yes, a 2.45 will not take another ratio.
the pinion is in a different spot in relation to the ring gear.
ask me how I know...
Don't be scared, pull it out and post pics on here.
Everyone will pile on and walk you thru it.
Dany and I have done that A LOT on her project when we get over our head and we have NEVER gotten bad advice!!