In the process of finishing up doin the upper and lower intake manifolds. The kit I am using came with two different sized O-rings, both brown in color. The stock O-rings appear to be the same size for the upper and the lower. Aside from which to use in each location, I was wondering if anyone had any tips to help get these on, they are not very flexible.

Thanks
Rick

Place them in a bowl of hot water. This should soften/expand them enough to "roll" them on like a "condom".

Wow Mike! I figured you would use small condoms, but not that small.

if you are talking about the dorman kit for intake you have to go get more because they are all the same and they only give you six for some reason. i just put some oil on it and rolled it on

You got the Fel-PRO MS98014T lower intake manifold kit right?

If that is the kit he got then they only give you six o-rings because they are for the lower tip of the injectors, I am pretty sure you do not get 12 of them because most do not totally remove the injectors from the fuel rail when doing the LIM job, of course the o-rings will also fit the top or bottom as they are the same size.
I was able to replace mine without doing anything more than lubricating them with some clean synthetic oil, or non synth if that is what you have, try to get one half under the lip of where it seats on the injector, and then roll the other side on, do not worry about stretching the o-ring a tad while rolling it on, as long as it does not stay stretched too long it should be fine.