Camshaft Followers aka lifters.

Does anyone have any knowledge on camshaft followers aka lifter? I have a 2006 Aveo which had a tick for lack of better words. After doing some research I thought I would change or clean the lifters. I ordered a couple P/N 617-0026 which showed to be compatible at many websites. Well I have removed the original lifters and they do not look the same. They seem to be the same size differ inside. So I did some additional research and found the GM part number to be 96376400 which if I had seen that first I would have purchased. So my first question, is the 617-0026 really compatible with the 96376400 and second is there anything specific I should look at on the original lifters to see if they are malfunctioning? I have seen other lifters where you can depress them and if they are stiff they need to be replaced or cleaned but the original and the new seem to be stiff with no depressing noted. Any help would be greatly appreciated.