Engine and transmission interchangeability 1999 vs 1997 4.3 liter

Hi,
My 1999 GMC Sonoma, 4.3 vortec V6 Automatic, 2wd stepside pickup is in need of a motor (and possible transmission) as well.

I have the opportunity to get a 1997 GMC Sonoma, 4.3 vortec, 2wd automatic, fleetside pickup.

Would the engine and transmission be a direct swap?

I realize some sensors might have to be swapped out from the 1999. But are there major differences?

I'd like to swap out the motor and transmission in one fell swoop, if possible.

Thank you in advance.