Pistons with different size ring thickness

[BPiston]

I am going to pull out the engine of my 86 ranger next month. It is the 2.3 but previous owner said the engine came from an 88 or 89 mustang. Does not have the 8 plugs. I am taking the block to the machine shop to have the cylinders bored out. (30over) When looking for parts, (pistons and rings) I get two choices of pistons and rings to order/purchase. The ring thickness is different. Compression ring thickness of 2.0mm or 1.5mm. Why are there two choices? Which do I get? Will it matter since I am buying all new pistons? Hope someone can help. Trying to avoid to wait for actually removing the pistons and measuring to see which ones to get because I want the parts before hand. But if that's what i have to do then I guess that's what I will do.

 

[adsm08]

Some pistons had different ring thicknesses. I think it may be factory vs aftermarket. Figure out which pistons you want, then figure out which rings you need based on that.

 

[BPiston]

OK thanks. That is what I thought. I will get the pistons and the rings that match that piston. Thanks.