1978 Chevy K20 future build any help would be Appreciated!!!

[nekkidhillbilly]

well the easy way for allison dmax is to use the left side drop and ford axle. but your looking at about 4-5k for a used combo and then if you want it to hold alot of power look to another 3k in the trans. the np205 will withstand a dmax im not sure about the 203 but you still have to rebuile it and make adapter ring to get it to bolt up. how ever a built 454 is only going to make the same tq as stock dmax or less. if you want mpg the 203 is a bad idea. a 1000 hp dmax can still get 20 mpg its been done all it takes is the flip of a switch to go from economy tune on one to full blown monster. there badass but its going to eat up that 15k pretty quick. you could do a pre common rail ctd and dodge trans for much less but then you loose the allison and all tune capabilty plus the engine ways double. now on to gas. used is the way to go with any of these engines. a 6.0 4l80e would be my gas choice unless i found a 6.2 or 6l80e for a steal. a 6.0 with a tune and bolt ons easly would make 400 hp 400ft(450 in some models.) for 15k you could restore the truck frame off and do internal mods to make the 6.0 have 500 hp and still have cash left over. with a 205 and this combo mid teens in mpg are very easly obtainable.