Correct, that is a Model T axle and it is WAY too flimsy to work in any application other than a stock Model T. The hubs on the wide five drums do not fit properly on those spindles either, so they are out. You got your $20 worth on the wheels, but everything else there is junk.
I understand that you don't have much money coming in, but that is why it is extra important for you to do LOTS of research before wasting what little money that you do have on parts you can't use. Also - being on a budget is NEVER an excuse for ignoring safety and plain old common sense. I don't want to see you or anyone else hurt. It's great that you are interested in hot rods and you want to jump into your first build, but it seems you are a little over your head here. Read books, magazines, tech articles on the net, talk to people at shows - absorb any and all information you can BEFORE you make costly mistakes. "Costly" not referring to wasting $20 on a junk axle, but as in losing your life or worse yet someone elses. It may sound harsh, but it is a sad fact of life. Don't be a statistic! Besides, when we start having too many accidents due to unsafe media-described "rat rod" type cars, then we are all going to pay the price. Take a look at a lot of the crap that's on the road today. Trust me, it's coming. So let's start off on the right foot...
A bit more advice - buy the Mike Bishop/Vern Tardel book "How To Build A Traditional Ford Hotrod". You will learn LOTS about what you are attempting to emulate and it will give you a good background in the basics to build upon. I hope this didn't sound too harsh, but I think you need some direction here. Good Luck...