How tough is it to put in an engine block heater? 2003 SLE. Assuming coolant must be drained down, frost plug removed and refill system making sure to get air out.

Yes..the only thing in the way is the transmission. And it'* definately in the way unless you are going for a frontal install. In that case, it should be reasonably easy to access.

Would there be any advantages to putting the block heater in the rear as opposed to the front? Or one spot is pretty much as good as the other? And where would one get an aftermarket block heater that isn't junk?
I'm looking to do this now, and I need to get my coolant flushed anyway.

I've seen heaters that fit in the rad hose. I take it those aren't really going to do the job, or wont last long?

I would pick the frost plug with the easiest access.

I would go with the frost plug style as opposed to the heater hose style. The heater does not have a pump, and so circulation is due to warm coolant rising, and cold coolant falling. This causes a convection circulation that distributes heat through the engine.

I use my block heater all the time. Car starts so much easier when the blook isn't ice cold, and heat is available in the cabin much quicker than without it.

This is a question that I have wondered about. Recently I bought a magnetic heater that I was going to put on my 1994 Le Sabre but I could not find a suitable spot on this car. Years ago I had a block heater on an old IHC van. On the IHC van the block heater was 1KW unit that connected to the heater hoses. This was quite effective especially in ease of starting but it also improved the gas mileage significantly. It did of course draw 1 KW and it took less than an hour to heat the engine up pretty good.
I actually still have that heater so I might try putting on the Buick but the freeze plug heater might be a better choice. Anyone have a favored source for one of these freeze plug heaters?

I ended up putting one in the front frost plug. Easy job. About 1.5 hour. Drain the coolant, Pull the starter and the frost plug is right there. I believe way easier then the rear one.

I would go with the inline heater core version. You spend less time on the ground and less coolant is lost. And if your handy dandy with electrical/wiring, you could rig your blower up so it will blow warm air into the inside of your car.

Problem with that approach is you don't get good circulation of warm water throughout the engine. Warm water (like warm air) rises, so you want to put the heater at the lowest point in the engine you can. If you put it low, the warm water rises and is replaced by the cold water. If you put it high, it just keeps warming the same water. The other advantage of a block heater is its simplicity. If you have ever installed (or seen) one, it is just a simple electrical element hooked up to a 120V power cord. Absolutely nothing to fail unless the element burns out, and that is not likely since it is immersed in coolant.

Does the inline version have a pump?

Good point Roy.

I believe most of them do. This is something I was looking at before...

KAT'* by Five Star 12150 - External Tank Engine Heater | O'Reilly Auto Parts

This company has a neat non-magnetic engine block heater (mounts to oil pan with adhesive).

https://www.wolverineheater.com/default.asp