Wrathmonk Not in these days of Fixed Prices contracts they won't.
RAF via MoD says "We want what the Yanks have got"
British industry gets hold of the relelvant specs and cracks on. After a while is struggling mightly to meet the specs. MoD gets shirty; Yanks find it highly amusing, offering to take over the contract.
The guys at the coal face, determined to deliver what was asked for do a little digging and find out that the US version never met the specs and nobody thought to tell the Brits about all the waivers.