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HAULIN' IT · 08-11-2017, 09:38 PM

I put a 455 Olds (same block as your 425) in my '78 K truck back in the '90's (I also have a 455 in a 2wd truck so this is right up my alley). Too bad photobucket has dicked up the whole situation as I have some photos of mounts, ect. that won't show up any longer.
With a little planning & some small steps made in the week prior...I was able to do the swap from a 350 Chevy to the big Olds in the 4X4 over a weekend. I was younger then too though!

A few things to work out will depend on what you have now. I have done the motor mounts 2 different ways using the Olds rubber mounts & frame stands but have seen guys use the Chevy rubber mounts & adapt the upper to the Olds block. On the 4X4, I added 1 1/2"x 1/8" plate to the front of the plate the frame mount sits on & bolted the mounts in the "forward" position on the block. On the 2wd, I made a plate across the 3 bolt holes on the block & then placed the mount in the center to sit in the "correct" place on the crossmember. Either way works fine.
On the 2wd, I'm using the HEAVY TransDapt adapter plate to mate up to a 4L60e...which is a fine way to go. Just stay away from the cheapy $75 thin plate version. On the 4X4, I had the output shaft installed in a multi-bell TH350 prior to the swap in preparation...never even changed the trans. dipstick tube...I just put a nut on the bolt though the bell housing.

The upper rad hose will need to be for an Olds, the lower from the truck works great. Fan shroud, ect all works fine. Just need a little longer rubber hose for the fuel line to the pump. Exhaust manifolds work out good. I suggest getting the Left battery tray for a diesel set-up to neaten up the battery cable. Depending on which oil filter housing you have it may need changed to clear the front driveshaft, but there are several versions & all 260-455 Olds interchange.

You will need to shuffle a bit of wiring due to the starter on the opposite side, however it works out fine. You will need to lengthen the oil & water sending unit wires, but that is about it.

That should cover it, but if you have any questions...just ask! Oh, by the way...you will Love the low RPM, BIG torque of the Olds! Lorne

08-11-2017, 09:38 PM	#5
HAULIN' IT Registered User Join Date: Dec 2015 Location: Beaver Falls, Pa Posts: 165	Re: Oldsmobile 425ci into 71 K10. I put a 455 Olds (same block as your 425) in my '78 K truck back in the '90's (I also have a 455 in a 2wd truck so this is right up my alley). Too bad photobucket has dicked up the whole situation as I have some photos of mounts, ect. that won't show up any longer. With a little planning & some small steps made in the week prior...I was able to do the swap from a 350 Chevy to the big Olds in the 4X4 over a weekend. I was younger then too though! A few things to work out will depend on what you have now. I have done the motor mounts 2 different ways using the Olds rubber mounts & frame stands but have seen guys use the Chevy rubber mounts & adapt the upper to the Olds block. On the 4X4, I added 1 1/2"x 1/8" plate to the front of the plate the frame mount sits on & bolted the mounts in the "forward" position on the block. On the 2wd, I made a plate across the 3 bolt holes on the block & then placed the mount in the center to sit in the "correct" place on the crossmember. Either way works fine. On the 2wd, I'm using the HEAVY TransDapt adapter plate to mate up to a 4L60e...which is a fine way to go. Just stay away from the cheapy $75 thin plate version. On the 4X4, I had the output shaft installed in a multi-bell TH350 prior to the swap in preparation...never even changed the trans. dipstick tube...I just put a nut on the bolt though the bell housing. The upper rad hose will need to be for an Olds, the lower from the truck works great. Fan shroud, ect all works fine. Just need a little longer rubber hose for the fuel line to the pump. Exhaust manifolds work out good. I suggest getting the Left battery tray for a diesel set-up to neaten up the battery cable. Depending on which oil filter housing you have it may need changed to clear the front driveshaft, but there are several versions & all 260-455 Olds interchange. You will need to shuffle a bit of wiring due to the starter on the opposite side, however it works out fine. You will need to lengthen the oil & water sending unit wires, but that is about it. That should cover it, but if you have any questions...just ask! Oh, by the way...you will Love the low RPM, BIG torque of the Olds! Lorne