Converting a 1984 s10 from 4-banger gas to a 6.2L diesel engine can be done however there are a few things to consider: Added weight on front end—a 6.2L has a dry weight of 702lbs—will all suspension and steering handle it.; the added weight of the larger rad; trans and everything else to complete the project.; A rear end to handle the added torque.Will the frame handle all the weight and stress. Putting the 6.2L into that small of an area will create heating problems for an engine that likes to run on the cool side. The exhaust system is going to be a nightmare to install. And when done a truck that is not going to handle very well with a frontend that is overly heavy and no weight on the back end(makes for a fun time in the winter). One solution is to find a compatible sized diesel donner and do a swap that way. OR Use the s10 as a daily driver and look for a full size unit that is diesel all ready and build it up the way you want. A p/u or burb in the same year range will go for anywhere from 500 to 3500 depending of condition and options. I picked up (read stole) a 1985 ½ ton 4x4 with a new motor, transmission, trans-case for 2500 body in good shape—electrical left much to desire {see photo section-More toys}.
Good luck to you and if help is required do not be afraid to ask and we will help