Need a new blade for an old RECORD 04 2" smoothing plane. Is there any significant difference between RECORD and STANLEY plane blades for similar size models STANLEY blades LOOK similar but I'm just wondering - would they be interchangeable
They should be interchangeable.
You can buy a VERITAS PM-V11 BLADE FOR STANLEY & RECORD PLANES 2" which suggests the Stanley and Record designs are both very close to the original Leonard Bailey design.
Hock tools say *"Our 3/32" thick blades ... will fit 99.9% of Stanley and Record style planes with no modifications other than a simple frog adjustment."
For a different sized plane Paul Sellers wrote
Any 2 3/8″ iron, cap iron and lever cap will fit the No6. Stanley and Record will be interchangeable. It may end up costing you more than buying a complete No6 plane in the end though.