5.3+700R4+NP208=Will it work?

[CHEVY4LLTHEWAY]

I am currently kicking around the idea of replacing my old 350 with a used low mile 5.3 vortec out of a salvage or wrecked vehicle. I know the 5.3 will work with the 700r4 with a few adapter kits, but am not for sure on the np208. I know it will work with the 700 but I remember doing some research on this swap and had read if I remember correctly that a 208 wont work with a 5.3 because of an electronically controlled speedo cable issue because the 208 is a mechanically controlled one? Would appreciate it if someone could help me out here.

[83GMCK2500]

Yes, it will work. You have a few options.

[79Betty]

Theyake adapters for the speedo... Not cheap though. Or get a cluster out of a 91's burban. Have electro speedo.

[Plunkett]

I was wondering about doing this swap and the speedo signal for the computer. On the 87 models, don't they have a speed sensor alin the transmission to give the ECM for the tbi a reading? Please correct me if I'm wrong on that.

[Jonboy]

Originally Posted by Plunkett

I was wondering about doing this swap and the speedo signal for the computer. On the 87 models, don't they have a speed sensor alin the transmission to give the ECM for the tbi a reading? Please correct me if I'm wrong on that.

'87 still uses a cable and an optic sensor, which is set up for 2000 pulses per mile (PPM). While the '91 Cluster will work with the 4000 PPM that is generated from the LS PCM, in it's TBI configuration the 2K signal was changed via a DRAC. There was a discussion on the LS swap board about what to do for a speedo signal; it looks like Dakota Digital now sells a 4K PPM pass through (it will let you retain your speedo cable and send the 4K PPM VSS signal you need for the LS to behave properly) VSS. It is pretty reasonably priced. To use your 700R4, you will have to find a way to adapt your TV cable to the throttle body you will use. I believe you will need a spacer to go from the flexplate to the converter.

[carboncrew]

2 wd has it in the trans or in the transfer case if its a 4x4. You could use one from the tranny even on a 4x4. Just realize that when in 4 wheel drive the computer will be getting wrong speed signal. You could find a 241 out of a 89-91 suburban. They will bolt to 700R4 and have VSS signal for your computer. You could then sway a cluster from suburban. Then you would have a speedo as well.

[nekkidhillbilly]

the make a vss that screws in just need to know the right pulse rate. idk why you would use a 700r4 over a 4l.60e though that comes on a 5.3

[nekkidhillbilly]

http://www.jagsthatrun.com/Pages/Spe...eedometer.html

[Flatpat]

Done it a couple times now. Pretty easy if you spend a little $$ on adapters. I use advance adapters for motor mount adapters and flexplate/spacer and you can get a pass through VSS speedo sensor from Dakota digital that you can wire into the computer and still let's you use your cable speedo. There are cheaper ways to go about the motor mount adapters and flexplate/spacer if you do a little looking.

[Flatpat]

Also the 5.3 uses metric bolts to bolt up the trans to the motor.

[CHEVY4LLTHEWAY]

Adding all of these adapters kinda makes it sound like a little to much and dont know if it will hold up. Could I just get a matching 5.3 and 4l60e 4x4 trans as a pair and get an adapter for the NP208 to fit?

[83GMCK2500]

Originally Posted by CHEVY4LLTHEWAY

Adding all of these adapters kinda makes it sound like a little to much and dont know if it will hold up. Could I just get a matching 5.3 and 4l60e 4x4 trans as a pair and get an adapter for the NP208 to fit?

Did you look at the adapter options? They consist of one component added between the speedometer drive and the cable, or are one unit replacing your existing speedo drive. Here are a few, again:

Jaguars That Run
PATC
Dakota Digital

If you want the 5.3 to run under fuel injection you need a VSS signal. The most reasonable way to achieve this AND keep the NP208 is to use one of the afore mentioned VSS generators. Your other option is to find the ONE-YEAR ONLY NP241 transfer case from Model Year 1991. The Suburbans, Blazers, and Crew Cabs produced in 1991 had electronic speedometers and therefore electronic VSS sending units as opposed to the mechanical speedo units.

[Jonboy]

Originally Posted by 83GMCK2500

Your other option is to find the ONE-YEAR ONLY NP241 transfer case from Model Year 1991. The Suburbans, Blazers, and Crew Cabs produced in 1991 had electronic speedometers and therefore electronic VSS sending units as opposed to the mechanical speedo units.

The 241 was used in '90& 91. It may have been a running change, but the electric cluster was in most (all?) of the '90 model V trucks. Not sure about the R series, so it may have been a running change. '91 R/V all used the electric cluster. This might make finding a transfer case easier, but if the Dakota Digital piece works as slick as it looks like it should, that is the way I would go. For ease of making it shift, I would figure out what you need to do to get a 4L60 to mate to the 208 case.

*full disclosure, I haven't had a 4x4 in almost 20 years. What swaps and what doesn't as far as transfer cases, transmissions, etc. is pretty fuzzy now.*

[nekkidhillbilly]

Originally Posted by CHEVY4LLTHEWAY

Adding all of these adapters kinda makes it sound like a little to much and dont know if it will hold up. Could I just get a matching 5.3 and 4l60e 4x4 trans as a pair and get an adapter for the NP208 to fit?

if you get the whole thing from a newer truck you can grab the oem 4 bolt to 6 bolt adapter off the newer truck. it would be the best set up. 4l60es dont cost alot.

[77dwh]

I recently did the same swap in my 77 k10 4x4. I swapped in a 2000 5.3 4l60e and 91 suburban 241 with the matching suburban cluster worked flawlessly.

[chevy-fun]

the 700r4 will not hold up unless its extremely built. mine only lasted 2-3wks but i beat on my truck