GM Engine differences
 

Does anyone know the differences between the L86, L87, and L89 engines. My 84 Jimmy is getting tired and I am going to replace the small block with an LS

Not sure what information you are trying to obtain here, but if you are going to put an LSx into it, why bother with the Lxx engines?

What trans are you going to use with the LSx?

I happen to know 2 of 3 answers because I own one of these. The L86 is a direct injected 6.2L Gen V which makes it an LT, not an LS. It has 420hp / 460 lb torque. It is the same long block as the Corvette / Camaro, with a forged crankshaft. The L86 has the taller, truck intake to make the power band more suitable for light truck use. It also has a more restrictive exhaust, IIRC. The L86 has the AFM (Active Fuel Management, can run on 4 cylinders). Both the L86 and L87 are premium fuel recommended engine. The L87 is the same engine, but with flex fuel capability. The L87 may have also introduced the Digital Fuel Management system, i.e. can run on various cylinders. My 2019 Yukon Denali is an early 2019, so I suspect the L87 was introduced later in the model year.
https://cimg7.ibsrv.net/gimg/www.gmf...6de188a41b.jpg

The L86 has a vacuum pump where the traditional power steering pump would be. The L86 also has an offset water pump, rather than in the center of the block.
https://cimg1.ibsrv.net/gimg/www.gmf...3a133143d5.jpg
https://cimg4.ibsrv.net/gimg/www.gmf...b1c1f05986.jpg

Thanks. There are several for sale from wrecked vehicles. All I knew was that they were all 6.2 liters and most people think they are Ls3's which they are not. I am finding out that they have more torque and develop it at a lower RPM. I am just trying to figure out which one I want in my Jimmy. I appreciate the information.

I am looking at wrecked vehicles at the salvage pool. The trans will be a 10L80 or 10L90 Depending on what engine it has in it. I want to buy the entire vehicle so I can use the steering column as well.

The L86 and the 10 speed is a very impressive combination. I didn't think I would like the transmission, but it does seem to work very well. The ability to shift in a 'close ratio' type action (staying right in the peak torque range) in heavy (but not WOT) acceleration is quite impressive. I just wish there was a dip stick on the transmission, as I do like regular 'spill and fills' of fluids. I keep vehicles too long. This Yukon may break me of that habit.