I am thinking about buying a ls1 for this 84 chevy c10. What all would i have to buy for the swap to the older model truck?

In short, a lot of stuff. Motor mounts, transmission mount to start out with. Without knowing what drive line is currently in the truck it's hard to continue. Did it have a 6 or an 8 before? Stick or Auto? And what condition are things like the radiator and charging system in? When you put the LS1 in, do you want auto or stick? If stick, 3, 4 5 or 6 speed? If auto 2, 3, 4 or more speeds? Is the LS1 injected, port injected or throttle body? Or are you going with a carb? Are you leaving the LS1 stock? Or did you plan on perking it up some? If so, how much more perk? All of these items come into consideration doing a swap; especially know what driveline is in it now? If it has an 8 you might be able to reuse a lot of it; if its a 6; there a lot more you have to change.

You also must consider suspension, room for accessories, bigger radiator, and what ever it takes to run your set up. Look at Summitt Racing on line, they sometimes carry what is needed to do swaps. there are a lot of after market car catalogs that offer what you may need. After making a list of all that you need, run up the cost and see if it will be what you intended to spend. It will be expensive. Coss71 is spot on. A lot of decisions must be made. One decision to change one thing will mean changing a lot of other items to accommodate everything.

Years back I had a 75 1 ton Chevy I picked up cheap; it had the 292 I6 in it with 3 on the tree. I spent 6 months collecting parts for the conversion; the salvage yards knew me very well. I used a lot of parts out of a 454 Suburban; the radiator, core support, trans mount etc.. The motor and trans I used was an LS1 out of a 81 impala along with it's 350 turbo trans. In my case I border the motor 50 over, used a 400 crank, 194 heads, cam, roller rockers, high rise manifold, edelbrock 600cfm square bore carb. That engine rebuild time was during that 6 month time frame. The motor mounts, trans mount, tranny cooler, floor shifter, custom made drive shaft, and a bunch of other items were all new from places like Jegs, Summit and some local speed shops. Excellent performance when I finished, but I spent more than I ever thought I would.