I have a few general questions about which engines and transmissions are compatible without special parts.
I have a 97 blazer(4wd) and a 96 s10(2wd) both with 4.3 vortec engines.
Im thinking of getting another s10 later.
I also want to get some vechicles for parts if i can find them cheap. So i am wandering what i should be looking for to keep everything compatible.

I assume i need to keep within the same generation (95-05) and all vortec 4.3. But i wander about some of the combination I will list below, but feel free to volunteer any else that might help me consider what to get.

Is all the 4.3 vortecs the same , from s-10, blazer, and even full size ?
will the engine / trans / 4wd be the same between blazers and s-10.

Are the older generation compatible enough to bother with for any parts?

Would the transmission of a 4.3 blazer and a 4.3 fullsize truck be the same (assuming they were both 2wd or 4wd)?

Any thing to avoid ?Thanks in advance.I wont be able to reply for a week or so though.

 

95 is the CPI engine, not the SCFI engine used from 96 thru mid-02. Mid-02 thru end of production was the MFI 4.3L which, besides the lack of an EGR valve and the MFI spider, it is practically identical to the SCFI motor.

With transmissions, you want to go newer if you can. A 4L60E from 96 on will work, but you get the benefits of updates the newer you go.

Transfer cases, you basically want to swap that for the same thing you have to keep it simple.

 

Ok i have been studying things some, so please tell me if i have some of this incorrect, or incomplete.

All the 4.3L come with a 700-r4 or a 4l60e auto transmission. the 700-r4 is older and does not require the computer to shift. The 4L60e is newer and does require the computer to shift. It should be possible to use a 700-r4 in place of a 4L60e if you flash or replace the computer with a computer programmed for a standard transmission.

The 4x4 and 4x2 auto transmissions are the same but the 4x4 have bolt holes for the transfer case , so its not possible to use a 4x2 transmission in a 4x4, and keep the 4x4 working. So a 4x4 transmission should work in a 4x2.

All of the 96-05 4.3 engines are similar, and interchangeable if you have the computer to go with it.

A 4.3 1/2 ton full size will have the same engine/transmission at the blazer / s10.

But i have a few specific questions:

1) what standard transmissions were available for the s-10 and blazers ?
2) would a standard transmission be interchangeable with an automatic if you had the computer to go with it ?
4) are the external parts (starter alternator steering water pump) the same for older 4.3 (older than 96) and newer 4.3 vortecs ? What about the block and internal parts ?
Are the s-10 4x4 and the blazer 4x4 (96-2004) transfer case, differentials, etc (4x4 components) interchangeable ?

I realize most of this doesnt really matter because i wouldnt actually swap such different parts , but im curious.

As per my original post, i believe i should stick with 96-2004 4.3 vortec s-10 or blazers with automatic , and preferably 4x4.

 

With the transmissions, the 4L60E was used from '93 on up, but did go through a rather substantial control change in '95. The newer transmissions will have PWM written in raised letters on the pump cover (behind the torque converter). The non-PWM and PWM transmissions cannot be swapped.

There was also a change in the case design. Sometime between 96 and 97, the transmission case changed from a single piece case to a two piece case. At the same time, there was also a change in the bolt pattern on the back of the transmission from 4-bolts (old) to 6-bolts (new). If you try to put a two piece case into an earlier PWM 4wd application, you will also have to find the transfer case adapter for your transfer case from the newer vehicle.

The difference between the 4wd & 2wd transmissions is quite simple. The 2wd output shaft is longer than the 4wd. But to swap the tail shaft, you must gut the transmission...

On the engine. From '96 thru mid-02, the engines are very similar. In 96 & 97, there was an additional port on the lower intake manifold near the thermostat for the PCM ECT (engine coolant temperature) sensor. In the '98+, the ECT and the temperature gauge sending unit were incorporated into one sensor on the driver side cylinder head.

After mid-02, the engine VIN was changed to an X which was for the change in the injection system to an MFI setup (backwards compatible to the SCFI VIN W engine), but these newer engines also removed the EGR system. The lower intake manifold does not have the provisions for an EGR so if you are using one of these engines in a 96 thru mid-02, you will have to use the lower intake manifold from your engine. Another difference in these newer engines is in the knock sensor and it's attachment. The newer knock sensor cannot be used with an older PCM, they are not compatible. The newer knock sensor bolts on while the old one threads in. To use a newer block in an older application, you must drill and tap the back of the block for the older knock sensor.

The last difference is in the oil pans. In 96 & 97, it seems to be a toss up as to whether you will have a stamped steel oil pan or a cast aluminum. In '98, they all were cast aluminum. I haven't looked through this point too much, but I suspect there is a difference between 2wd & 4wd oil pans. If you use the pan your vehicle currently has or at least compare with the donor engine, you should be set.

As far as the manual transmissions go, you will need to find a donor truck. One from an older truck should work, but you do need to get the PCM reprogrammed to work.

You can compare part numbers at your choice of online parts stores to determine interchange on exterior items. The internals are quite different depending on the case... It really isn't worth it to try and find stuff to try and fit in... Just use the proper parts and you should be fine.