Hello, I am planning to replace an engine in a 99 trailblazer 4x4 (4.3 vortec). It has engine vin code W. I found an engine from a 98 blazer also 4x4 (4.3 vortec). The engine is out of the vehicle so I have no way to see if it has the same engine code. Can anyone tell me if they are the same or what I should look for? Thanks

 

There is next to no differences between the 99 and 98 s-series 4.3L with the possible exception of a few codes here and there on parts.

The only real differences you would need to look out for is in the mid-01 and newer engines as they changed the knock sensor mounting as well as did away with the EGR valve. Nothing that cannot be overcome if you are prepared and know what to look for.

 

Thanks for the reply. I found this info on wikipedia. Is this anything to worry about?
"Crankshafts manufactured for the 1999 model year (to the end of 4.3L production) had a pilot hole depth of 1.410" when coupled to the LSx-based 4L60E, which had a redesigned torque converter pilot hub which is longer and used with a 300mm stator shaft). The torque converter pilot hub is longer than the early 4L60E (similar in appearance to the 700R4 c. 1993-95) or the second generation variants (incorporating a removable bellhousing) with the GMT330 or 1996-2000 C/K series."

 

That might be true for the C/K fullsize trucks which is why I stated S-series. The S-series trucks were never equipped with the LS-based 4L60E.

Besides, if I am reading that correctly, the pilot hole is deeper in the newer crankshafts which should not prevent backwards compatibility even if the donor 4.3L came out of a newer fullsize truck. The information you posted does not list a change in diameter, only in depth of the pilot hole and corresponding pilot hub on the converter. You can tell that the engine was originally installed on an LS-based 4L60E by the presence of a threaded hole in the center/top boss which is not used on the earlier bolt pattern transmissions. This hole started being used because the next lower bolt location on the passenger side would enter the water jacket on an LS engine so they didn't use it.

 

Thats great news. Thanks for all your help Swartlkk!