[Zoomad75]

The first few years of GM IFS systems used a thermal actuator which was extremely problematic as you already know. They later switched to a fully electric actuator which is much less problematic. The GMT800 trucks and later were all electric as far as the front diff actuator works. They don't fail like the old ones.

As far as the spider gears turning from one side driving them all the time, again that hasn't been an issue. As long as the fluid in the front diff is at the correct level, the gears are fully lubricated. I've yet to see a front diff in the dealership where I work with 50,000 miles, 100,000 miles or higher where the spider gears were wiped out from normal use with mostly 2wd operation.

I prefer my solid axle in my K5 with the manual locking hubs, but the issues that came from the early IFS systems are no longer there. The trucks are very reliable with normal maintenance. I'm not a fan of pushbutton or rotary knob style electronic t-case shifting, but they haven't been an issue compared to the early years. I recommend anybody that has an electric shift t-case to shift it through the ranges periodically to allow the feedback switch to move with the shift arm to keep it from hanging up. If the feedback switch (that reports the actual shift position to the computer) hangs up or does not move in the correct amount of time the computer will abort the shift and throw it back in the range it came from.

The #1 issue with the rotary knob style shifter for t-cases is moving the knob with the key off. The system will not change ranges with the vehicle shut off and won't respond to the change in position when the key is turned on. What happens is the system will stay in the last range it saw before shutting off and won't respond to any new change to the knob position. The only way to get it to work again is shutting the truck off, moving the knob to where it was before and then turning the truck back on. The tiny little indicator light on the edge of the knob will light up again and follow any new change in position.

Keep this in mind, any IFS truck from any current manufacturer domestic or foreign will work the front axle disconnect in the same concept as the GM system. If I'm not mistaken even the Ram and Jeep solid front axle setups use a similar front axle disconnect to not have to run locking hubs at the wheels and allow a true shift on the fly to 4wd type setup.