Swapping 88 318 for 79 360

underdogrow · Aug 17, 2015

I'm about to pull the 318 tbi and 904 transmission out of my 88 D-100. I picked up a 360 magnum and tf8 727 trans for 450.00. My biggest concern is the length of my driveshaft I'm hoping it will fit Right in. I'm leaving the factory 8 1/4 rear end for now despite its weaker components I am on a budget. Well the new motor and trans fit Right in? Am I over looking issues with bypassing the pcm?

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HemiLonestar · Aug 17, 2015

They will bolt in, you could have issues bypassing the PCM, personally in an 88 I'd either go full EFI conversion or considering you're putting an older engine into a newer chassis (which is usually illegal with emissions laws) convert it to a carb. There are some pretty good aftermarket TBI kits that will work nicely. Your stock driveshaft will be a bit too long as the 904 and 727 are different lengths, however you should be able to find a stock replacement as the 727 was an optional transmission. I would've looked for a newer magnum engine (you said 360 magnum, but you said it's out of a '79, no such animal) and hooked it to an A518, which is basically a 727 with an OD unit on it.

underdogrow · Aug 17, 2015

Thank you for clearing that up, I've been fighting the 88 tbi system for the better part of two months now. When I got it I didn't realize the extent of work a previous mechanic had put in to bypass those emissions solenoids. I started by replacing the in line pump they had ran, I'm guessing to bypass this system
. I'm assuming when I reinstalled the factory fuel pump (new) I was unknowingly back to square 1. This motor and transmission I've decided to put in is stock from a 79 3/4 T crew cab. Holley 4 barrell. Picked it up on craigslist for 450.

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underdogrow · Aug 17, 2015

I know I would have been better of with something more efficient but money is tight and I need my truck back on the road

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underdogrow · Aug 17, 2015

One more thing will a shift kit get me sonewhere in the ballpark of the efficiency of an A518

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HemiLonestar · Aug 19, 2015

underdogrow said:
One more thing will a shift kit get me sonewhere in the ballpark of the efficiency of an A518

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No even close. That older automatic is a 3 speed, the 518 is a and overdrive trans. Shift kit will help it shift better, but that's it. If it's out of a 79 then it might not even have a lockup TC.

underdogrow · Aug 26, 2015

That was a dumb question found out shortly after posting

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underdogrow · Aug 28, 2015

I've run into a few more questions. This 727 has a short tailshaft the entire length measures only 27 inches. From what I've researched it has a fixed yoke. Dies that

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underdogrow · Aug 28, 2015

Does that mean I need a two piece shaft? Also I'm worried about my transmission mount lining up. If it doesn't will I need a new crossmember or just the mount itself?

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underdogrow · Aug 28, 2015

By mount I mean the plate attaching kit to the crossmember

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underdogrow · Aug 28, 2015

My rookie is showing bad. Short tail shaft 727 slip yoke compatible? Two piece shaft?

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Swapping 88 318 for 79 360

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