Transfer cases compatibility

Hi everyone, again i need your expertise, im going to buy a rebuild transfer case, i have an 18 splines big bearing and from where im going to buy he has an 18 splines small bearing. He told i can use the small bearing there s no a big difference like the big bearing in being more heavy duty. What do you think? Btw i showed the pictures of the splines told me they are 75% worn out, so i need to change asap.
Thanks for your help guys.

Only two things to worry about when putting in new transfer case, correct spine count and gear ratio. The bearing size doesn’t matter.

Thanks for your advice, so im ok with the small bearing coz thats the only difference from, both are 5speed 18 splines.