72 K20 4spd ls swap

[Haybag]

Working on a 72 K20 with a 350 and 4spd set up with my son for his first vehicle. Want to make a reliable driver for him, this 350 would need quite a bit of help to be reliable. I put a 4.8 in my 72 C10 a couple years ago and love it. What sort of extra challenges are involved in putting a 5.3 into this 72 k20 with the original 4spd? Also this truck has a 4" lift if that helps with clearance issues.

[gpgofast]

Originally Posted by Haybag

Working on a 72 K20 with a 350 and 4spd set up with my son for his first vehicle. Want to make a reliable driver for him, this 350 would need quite a bit of help to be reliable. I put a 4.8 in my 72 C10 a couple years ago and love it. What sort of extra challenges are involved in putting a 5.3 into this 72 k20 with the original 4spd? Also this truck has a 4" lift if that helps with clearance issues.

Just did a 6.0 LQ4 in my 1971 K20 with an SM465/NP205. There will be a few challenges but nothing really big. You will want to slide the motor forward as much as possible. I used stock cross members and elongated/relocated holes to move it forward about 1/2 inch. 1 inch would have been better, firewall clearance is an issue with the heads. Also, exhaust manifolds with the clutch linkage also is not doable. I used Speed Engineering block hugger headers. ICT Billet motor mount plates with stock motor mounts. I swapped in a bell housing/clutch slave cylinder from a mid 1980's Chevy. Used clutch and flywheel off a ~2000 Silverado.

[Haybag]

Thanks! That is good info.

[hevy_chevy67]

I'm also thinking about putting a 5.3 into my K10.
If I'm keeping the NP205 and 4 speed, does everything have to get shifted forward? Is it going to require driveshaft changes?

[gpgofast]

Originally Posted by hevy_chevy67

I'm also thinking about putting a 5.3 into my K10.
If I'm keeping the NP205 and 4 speed, does everything have to get shifted forward? Is it going to require driveshaft changes?

I only shifted mine forward about 3/8 of an inch. If I was doing it again I would shift it forward probably a full inch. My driveshafts did not need to be modified.