The end of US Presidency timing of this week's Mark 48 torpedos-for-Taiwan announcement (see more details below) is suspicious and may signal lack of US resolve. In a few months the Obama Administration won't be around, so won't need to honor the Mark 48 deal. A deal that may be years until delivery.
Alternatively it may be just Taiwan that is doing the announcing in order to persuade an incoming Clinton or Trump Administration to provide more US help for Taiwan's decades long aim of receiving new submarines. Taiwan's own budget for a US assisted new submarine program is amazingly low - for example Taiwan expects to pay only $95 million for the design phase for a completely new submarine of 1,000+ tonnes. One billion dollars for a new submarine design would be more typical - presumably Taiwan expects the US to contribute the bulk of the design and all other costs.
The cutaway diagram (above) is of Taiwan's latest 2 submarines of the Hai Lung class, (aka "Chien Lung" class) due to be armed with Mark 48 torpedos, but in several years time.
The Taiwanese Government has announced that the US will be supplying Mark 48 heavyweight torpedos for Taiwan's two relatively modern subs. The Mark 48s (see diagram and Youtube below) are for Taiwan's two 1980s Dutch built Hai Lung (aka Chien Lung) class submarines. The current torpedos on the Hai Lungs are listed (right sidebar) as being German made AEG SUT (264s?).
The two Hai Lung's will be undergoing life extension programs over the next few years. The life extensons are presumably at different times to allow at least one Hai Lung to be operational. They are also likely to receive modern, but basic, US combat systems (see Diplomat pay-site).
Taiwan's other two submarines (1940s-50s era US built) named Hai Shih and Hai Bao - are simply too old for weapons modernisation and are probably not operational.
Mark 48 torpedo is second from top on this diagram.
Australian Collins sub fires Mark 48 at target ship. Dramatic WWII style voice-over and music!