Will a 1994 Chevy Suburban transmission fit 2001 Suburban?

No, a 1994 Chevy Suburban transmission will almost certainly not fit a 2001 Chevy Suburban. While they're both Suburbans, GM made significant changes to their transmissions and drivetrains between those model years. The bolt patterns, bellhousing, and even the overall design will likely be incompatible. You'd be facing major, likely insurmountable, adaptation challenges.