911 3.0 case question?

[klober23]

I am looking at a 911 3.0 case #930.101.104.4R . The case came out of a 78-83. What is the difference between the 4R and 5R castings? Is this case as good as a 930 turbo? What are the differences if any? Thanks

[Henry Schmidt]

The difference between castings is that the 4R has a sump on the bottom.
The 5R case is a none sump plate case.
Turbos and non turbo cases were the same except for the studs they were delivered with.
Turbos came with 24 Delivar studs and 911 SC cases came with 12 steel and 12 Delivar studs. That was why there were two part numbers.
There are some people that believe the non sump plate case is stronger. I have no evidence to prove or disprove that but the 5R case certainly has less places to leak.

4R
5R