2 1/2 gauge HALL project dont know which loco,First wheel to 2nd =4" and 2nd to 3rd= 4 1/4 hope that helps.Looks like its inside valve gear or 3 cylinder .well made by B E E Boilers.Had to tye wrap wheels they are not set.Sorry no more info on it but you have to make own mind up.Sorry bought as seen. or been told could be lms jubilee so been told different info so will need to make your own mind up .i dont have a clue