PowerEdge T420 with 4 FXO for Elastix commuication card

I was wondering if someone could confirm with me the compatibility of this card. I have a T420 that has Supported PCI Express Generation 3 Expansion Cards from what I read in the document. This means it backwards compatible right? The FXO card is a PCI-Express compliant analog card with 4 ports FXO/FXS Interface: PCI-Express X1 looking at this link you can see this is a very short card insert. The slots I have on this server, the ones that are long say PCIE_G3 and the a little smaller ones I see are PCIE_G2 https://www.alibaba.com/product-detail/4-Ports-with-4-FXO-for_1083054256.html?spm=a2700.8443308.0.0.45b33e5fulEx10 Would I have any trouble installing this card? thanks for the help, Guy