Block number 25506818 is this a 3.8 or a 4.1

[the wrath]

Gnttype.org says its 4.1 but I googled it is says it's a early 3.8

 

[WarWagon]

TeamBuick resource, has that a 1979-87 3.8L

 

[earlbrown]

Measure the bore. stock 3.8 is 3.800" 4.1 is 3.965"