[SilverMk2]

The lower timing covers (inner and outer) are exactly the same between the 5 and 6M. From what I remember I used both the orginal 5M cover on my 6M when I rebuilt it. From what I recall the 7M rear lower cover is a little different than the 5/6M one around the water pump. You do need to remember to use a 7M front main seal with the 6/7M timing cog (the ID is bigger). The 8.8:1 pistons will give you 8.8:1 compression with the 5M head one. Piston pin location is the same. If it isn't you are screwed the pistons come flush with the block deck at TDC and the clearance is the HG thickenss (maybe .030" compressed or so?), so they can't go up much higher.

 

[SilverMk2]

Oops my mistake, yeah it would be 9.2:1 with the flat top domes (just like a 6M :twak. I'm thinking 5M crank in a 7M :drinking: . I just can't seem to get that concept out of my head at: .

I could be wrong on the 7M timing cover. Its been a while since I've looked at one.

 

[SilverMk2]

Looking in the EPC Toyota has different #s for the 5 and 7M rear lower covers. 11301-43020 (or 43010) and 11301-42010. Water pump has a different part # as well (outside shape and bolt pattern look different in EPC).