drift girl said that the sentra SR20 and the silvia SR20 are the same just that the sentra SR20 is for a front drive platform, my question is this can you turn the engine sidways and put in an 86 hardbody? If so what manual (5-speed,6speed) transmission will link up and fit in this truck?  

They use the asme block, but the internals are different. It would just be easiest to buy a front clip of a 180sx or Silvia. That comes with the tranny, ecu, motor, everything you would need.  

no, they cannot be turned sideways. fwd sr20 out of the usdm 200sx and nx 2000 have different engine mounts, intake and exhaust manifolds, transmission, and internals. the engine mounts are not moveable so its worthless to try. do like kyle said and get a front clip off the silvia for about 5k at the most

btw, kyle, the 180sx has the ca18det, different motor all together
but the silvia sr20det will fit in the truck if the truck already has a ka24de, direct drop i beleive.  

+1, any time you go from a transverse to a standard engine layout, there is going to be many parts that need to be sourced or fabricated.  also not been mentioned, the accessories might need to be relocated or changed (alternator and such)