Not sure about the Impala SS but I did try to look up the price difference on my GM parts computer between a mid 90's camaro LT1 and a 2000 camaro LS1 MAF. Couldn't beleive they were actually the same part number
My guess the'd probably be the same thing on the Impala. If I get some time tomorrow I'll try to check my computer at work.
i have an LT1 MAF i took off my 94 Caprice when i took the motor out of it, and an LS1 MAF that came with a blown up LS1 i bought afew years ago, and i can tell you they are totally different. the LS1 MAF is about 1/2" bigger, and the plug is different.
I put an impala ss on mine w/translator,and works great.I paid 80$ plus tx,but that was my cost at the dealer where i work,been about 4yrs ago.It was for a 96 ss good luck!